diff --git a/buildall.sh b/buildall.sh
index 0eabd8e..32b2463 100755
--- a/buildall.sh
+++ b/buildall.sh
@@ -16,7 +16,8 @@ old="unset"
 release=""
 tmp=buildall.tmp.$$
 trial="FALSE"
-webappsdir="/var/lib/tomcat7/webapps"
+webappsdir="/var/lib/tomcat8/webapps"
+gitremote="origin"
 
 # Builds the build signature properties in the manifest map file
 # expected arguments: old version tag, version tag, full name of user,
@@ -72,11 +73,13 @@ if [ $# -lt 1 ]
 then
 	cat <<-EOF 1>&2
 	Usage:
-      -archive           Create a tar archive of the current state of the source.
-	  -build             Build all components and commit to master.
+    -archive           Create a tar archive of the current state of the source.
+	  -build             Build all components, commit and push to origin.
+    -docker            Build and push a Docker image.
 	  -email [ADDRESS]   Your email address, to be recorded in the build signature.
 	  -fullname [NAME]   Your full name, to be recorded in the build signature.
-	  -pull				 Pull from remote git repository
+    -git-remote [NAME] Use the specified git remote
+	  -pull				       Pull from remote git repository
 	  -release [LABEL]   Build all components, branch for release on old label, then
 	                     upversion to new LABEL and commit to master.
 	  -trial             Trial build only, do not commit.
@@ -87,21 +90,26 @@ fi
 while (( "$#" ))
 do
 	case $1 in
-    	-a|-archive)
-      		archive="TRUE";;
+    -a|-archive)
+      	archive="TRUE";;
 		-b|-build)
 			# 'build' is the expected normal case.
 			trial="FALSE";
 			;;
+    -d|-docker)
+      docker="TRUE";;
 		-e|-email)
 			shift;
 			email=$1;;
 		-f|-fullname)
 			shift;
 			fullname=$1;;
-	    -p|-pull)
-	      	# pull from remote Git origin
-	      	git pull origin master;;
+	  -p|-pull)
+	    # pull from remote Git origin
+	    git pull ${gitremote} master;;
+    -g|-git-remote)
+      shift;
+      gitremote=$1;;
 		-r|-release)
 			# release is branch a release and upversion to new label
 			shift;
@@ -126,7 +134,7 @@ do
 	shift
 done
 
-echo "Trial: ${trial}; email: ${email}; fullname ${fullname}; release: ${release}; webapps: $webappsdir"
+echo "Trial: ${trial}; docker: ${docker}; email: ${email}; fullname ${fullname}; release: ${release}; webapps: $webappsdir"
 
 ls mw-* > /dev/null 2>&1
 if [ $? -ne 0 ]
@@ -137,132 +145,141 @@ fi
 
 for dir in mw-*
 do
-	pushd ${dir}
+  if [ "${dir}" != "mw-explore" ]
+  then
+    pushd ${dir}
 
-	# Make a temporary directory to keep the work-in-progress files.
-	if [ ! -d "${tmp}" ]
-	then
-		rm -f "${tmp}"
-		mkdir "${tmp}"
-	fi
+    # Make a temporary directory to keep the work-in-progress files.
+    if [ ! -d "${tmp}" ]
+    then
+      rm -f "${tmp}"
+      mkdir "${tmp}"
+    fi
 
-	cat project.clj > ${tmp}/project.bak.1
-	old=`cat project.clj | grep 'defproject mw' | sed 's/.*defproject mw-[a-z]* "\([A-Za-z0-9_.-]*\)".*/\1/'`
+    cat project.clj > ${tmp}/project.bak.1
+    old=`cat project.clj | grep 'defproject mw' | sed 's/.*defproject mw-[a-z]* "\([A-Za-z0-9_.-]*\)".*/\1/'`
 
-	if [ "${release}" != "" ]
-	then
-		message="Preparing ${old} for release"
+    if [ "${release}" != "" ]
+    then
+      message="Preparing ${old} for release"
 
-		# Does the 'old' version tag end with the token "-SNAPSHOT"? it probably does!
-		echo "${old}" | grep 'SNAPSHOT'
-		if [ $? -eq 0 ]
-		then
-			# It does...
-			interim=`echo ${old} | sed 's/\([A-Za-z0-9_.-]*\)-SNAPSHOT.*/\1/'`
-			if [ "${interim}" = "" ]
-			then
-				echo "Failed to compute interim version tag from '${old}'" 1>&2
-				exit 1;
-			fi
-			setup-build-sig "${old}" "${interim}" "${fullname}" "${email}"
-			message="Upversioned from ${old} to ${interim} for release"
-			old=${interim}
-		else
-			setup-build-sig "unset" "${old}" "${fullname}" "${email}"
-		fi
-	else
-		setup-build-sig "unset" "${old}" "${fullname}" "${email}"
-	fi
+      # Does the 'old' version tag end with the token "-SNAPSHOT"? it probably does!
+      echo "${old}" | grep 'SNAPSHOT'
+      if [ $? -eq 0 ]
+      then
+        # It does...
+        interim=`echo ${old} | sed 's/\([A-Za-z0-9_.-]*\)-SNAPSHOT.*/\1/'`
+        if [ "${interim}" = "" ]
+        then
+          echo "Failed to compute interim version tag from '${old}'" 1>&2
+          exit 1;
+        fi
+        setup-build-sig "${old}" "${interim}" "${fullname}" "${email}"
+        message="Upversioned from ${old} to ${interim} for release"
+        old=${interim}
+      else
+        setup-build-sig "unset" "${old}" "${fullname}" "${email}"
+      fi
+    else
+      setup-build-sig "unset" "${old}" "${fullname}" "${email}"
+    fi
 
-	sed -f ${tmp}/manifest.sed ${tmp}/project.bak.1 > project.clj
+    sed -f ${tmp}/manifest.sed ${tmp}/project.bak.1 > project.clj
 
-	echo $message
+    echo $message
 
-	lein clean
-	lein compile
-	if [ $? -ne 0 ]
-	then
-		echo "Sub-project ${dir} failed in compile" 1>&2
-		exit 1
-	fi
+    lein clean
+    lein compile
+    if [ $? -ne 0 ]
+    then
+      echo "Sub-project ${dir} failed in compile" 1>&2
+      exit 1
+    fi
 
-  	lein test
-	if [ $? -ne 0 ]
-	then
-		echo "Sub-project ${dir} failed in test" 1>&2
-		exit 1
-	fi
+    lein test
+    if [ $? -ne 0 ]
+    then
+      echo "Sub-project ${dir} failed in test" 1>&2
+      exit 1
+    fi
 
-	lein marg
-	lein install
+    lein marg
+    lein install
 
-	# If we're in the UI project, build the uberwar - and should
-	# probably deploy it to local Tomcat for test
-	if [ "${dir}" = "mw-ui" -a "${webappsdir}" != "" ]
-	then
-    	lein ring uberwar
-		sudo cp target/microworld.war "${webappsdir}"
-		echo "Deployed new WAR file to local Tomcat at ${webappsdir}"
-	fi
+    # If we're in the UI project, build the uberwar - and should
+    # probably deploy it to local Tomcat for test
+    if [ "${dir}" = "mw-ui" -a "${webappsdir}" != "" ]
+    then
+      lein ring uberwar
+      sudo cp target/microworld.war "${webappsdir}"
+      echo "Deployed new WAR file to local Tomcat at ${webappsdir}"
+    fi
 
-		# Then unset manifest properties prior to committing.
-	cat project.clj > ${tmp}/project.bak.2
-	setup-build-sig
-	sed -f ${tmp}/manifest.sed ${tmp}/project.bak.2 > project.clj
+    if [ "${dir}" = "mw-ui" -a "${docker}" = "TRUE" ]
+    then
+      lein docker build
+      lein docker push
+    fi
 
-	if [ "${trial}" = "FALSE" ]
-	then
-		if [ "${message}" = "" ]
-		then
-			git commit -a
-		else
-			git commit -a -m "$message"
-		fi
-		git push origin master
-	fi
+    # Then unset manifest properties prior to committing.
+    cat project.clj > ${tmp}/project.bak.2
+    setup-build-sig
+    sed -f ${tmp}/manifest.sed ${tmp}/project.bak.2 > project.clj
 
-	if [ "${release}" != "" ]
-	then
-		branch="${old}_MAINTENANCE"
-		if [ "${trial}" = "FALSE" ]
-		then
-			git branch "${branch}"
-			git push origin "${branch}"
-		fi
+    if [ "${trial}" = "FALSE" ]
+    then
+      if [ "${message}" = "" ]
+      then
+        git commit -a
+      else
+        git commit -a -m "$message"
+      fi
+      git push ${gitremote} master
+    fi
 
-		cat project.clj > ${tmp}/project.bak.3
-		setup-build-sig "${old}" "${release}-SNAPSHOT" "${fullname}" "${email}"
-		sed -f ${tmp}/manifest.sed ${tmp}/project.bak.3 > project.clj
-		message="Upversioned from ${interim} to ${release}-SNAPSHOT"
+    if [ "${release}" != "" ]
+    then
+      branch="${old}_MAINTENANCE"
+      if [ "${trial}" = "FALSE" ]
+      then
+        git branch "${branch}"
+        git push ${gitremote} "${branch}"
+      fi
 
-		echo $message
+      cat project.clj > ${tmp}/project.bak.3
+      setup-build-sig "${old}" "${release}-SNAPSHOT" "${fullname}" "${email}"
+      sed -f ${tmp}/manifest.sed ${tmp}/project.bak.3 > project.clj
+      message="Upversioned from ${interim} to ${release}-SNAPSHOT"
 
-		lein clean
-		lein compile
-		if [ $? -ne 0 ]
-		then
-			echo "Sub-project ${dir} failed in compile after branch to ${release}!" 1>&2
-			exit 1
-		fi
-		lein marg
-		lein install
+      echo $message
 
-		# Then unset manifest properties prior to committing.
-		cat project.clj > ${tmp}/project.bak.4
-		setup-build-sig
-		sed -f ${tmp}/manifest.sed ${tmp}/project.bak.4 > project.clj
+      lein clean
+      lein compile
+      if [ $? -ne 0 ]
+      then
+        echo "Sub-project ${dir} failed in compile after branch to ${release}!" 1>&2
+        exit 1
+      fi
+      lein marg
+      lein install
 
-		if [ "${trial}" = "FALSE" ]
-		then
-			git commit -a -m "${message}"
-			echo ${message}
-			git push origin master
-		fi
-	fi
+      # Then unset manifest properties prior to committing.
+      cat project.clj > ${tmp}/project.bak.4
+      setup-build-sig
+      sed -f ${tmp}/manifest.sed ${tmp}/project.bak.4 > project.clj
 
-	# if nothing broke so far, clean up...
-	rm -rf "${tmp}"
-	popd
+      if [ "${trial}" = "FALSE" ]
+      then
+        git commit -a -m "${message}"
+        echo ${message}
+        git push ${gitremote} master
+      fi
+    fi
+
+    # if nothing broke so far, clean up...
+    rm -rf "${tmp}"
+    popd
+  fi
 done
 
 
diff --git a/project.clj b/project.clj
index a2739ff..7bdb48c 100644
--- a/project.clj
+++ b/project.clj
@@ -1,4 +1,4 @@
-(defproject mw-engine "0.1.5-SNAPSHOT"
+(defproject mw-engine "0.1.6"
   :description "Cellular automaton world builder."
   :url "http://www.journeyman.cc/microworld/"
   :manifest {
@@ -12,10 +12,9 @@
   :license {:name "GNU General Public License v2"
             :url "http://www.gnu.org/licenses/gpl-2.0.html"}
   :plugins [[lein-marginalia "0.7.1"]]
-  :dependencies [[org.clojure/clojure "1.6.0"]
-                 [org.clojure/math.combinatorics "0.0.7"]
-                 [org.clojure/tools.trace "0.7.8"]
-                 [org.clojure/tools.namespace "0.2.4"]
+  :dependencies [[org.clojure/clojure "1.8.0"]
+                 [org.clojure/math.combinatorics "0.1.4"]
+                 [org.clojure/tools.trace "0.7.9"]
+                 [org.clojure/tools.namespace "0.2.11"]
                  [hiccup "1.0.5"]
-                 [net.mikera/imagez "0.3.1"]
-                 [fivetonine/collage "0.2.0"]])
+                 [net.mikera/imagez "0.12.0"]])
diff --git a/src/mw_engine/core.clj b/src/mw_engine/core.clj
index 9b95b55..83c1a2e 100644
--- a/src/mw_engine/core.clj
+++ b/src/mw_engine/core.clj
@@ -1,32 +1,56 @@
-;; Functions to transform a world and run rules.
-
-(ns mw-engine.core
-  (:use mw-engine.utils)
+(ns ^{:doc "Functions to transform a world and run rules."
+      :author "Simon Brooke"}
+  mw-engine.core
   (:require [clojure.core.reducers :as r]
-            [mw-engine.world :as world])
+            [mw-engine.world :as world]
+            [mw-engine.utils :refer [get-int-or-zero map-world]])
   (:gen-class))
 
-;; Every rule is a function of two arguments, a cell and a world. If the rule
-;; fires, it returns a new cell, which should have the same values for :x and
-;; :y as the old cell. Anything else can be modified.
-;;
-;; While any function of two arguments can be used as a rule, a special high
-;; level rule language is provided by the `mw-parser` package, which compiles
-;; rules expressed in a subset of English rules into suitable functions.
-;;
-;; A cell is a map containing at least values for the keys :x, :y, and :state;
-;; a transformation should not alter the values of :x or :y, and should not
-;; return a cell without a keyword as the value of :state. Anything else is
-;; legal.
-;;
-;; A world is a two dimensional matrix (sequence of sequences) of cells, such
-;; that every cell's :x and :y properties reflect its place in the matrix.
-;; See `world.clj`.
-;;
-;; Each time the world is transformed (see `transform-world`, for each cell,
-;; rules are applied in turn until one matches. Once one rule has matched no
-;; further rules can be applied.
-
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; mw-engine: the state/transition engine of MicroWorld.
+;;;;
+;;;; This program is free software; you can redistribute it and/or
+;;;; modify it under the terms of the GNU General Public License
+;;;; as published by the Free Software Foundation; either version 2
+;;;; of the License, or (at your option) any later version.
+;;;;
+;;;; This program is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;;; GNU General Public License for more details.
+;;;;
+;;;; You should have received a copy of the GNU General Public License
+;;;; along with this program; if not, write to the Free Software
+;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+;;;; USA.
+;;;;
+;;;; Copyright (C) 2014 Simon Brooke
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; Every rule is a function of two arguments, a cell and a world. If the rule
+;;;; fires, it returns a new cell, which should have the same values for :x and
+;;;; :y as the old cell. Anything else can be modified.
+;;;;
+;;;; While any function of two arguments can be used as a rule, a special high
+;;;; level rule language is provided by the `mw-parser` package, which compiles
+;;;; rules expressed in a subset of English rules into suitable functions.
+;;;;
+;;;; A cell is a map containing at least values for the keys :x, :y, and :state;
+;;;; a transformation should not alter the values of :x or :y, and should not
+;;;; return a cell without a keyword as the value of :state. Anything else is
+;;;; legal.
+;;;;
+;;;; A world is a two dimensional matrix (sequence of sequences) of cells, such
+;;;; that every cell's :x and :y properties reflect its place in the matrix.
+;;;; See `world.clj`.
+;;;;
+;;;; Each time the world is transformed (see `transform-world`, for each cell,
+;;;; rules are applied in turn until one matches. Once one rule has matched no
+;;;; further rules can be applied.
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (defn apply-rule
   "Apply a single `rule` to a `cell`. What this is about is that I want to be able,
@@ -37,14 +61,15 @@
    to access neighbours."
   ([world cell rule]
    (cond
-     (ifn? rule) (apply-rule cell world rule nil)
-     (seq? rule) (let [[afn src] rule] (apply-rule cell world afn src))))
-  ([cell world rule source]
+     (ifn? rule) (apply-rule world cell rule nil)
+     (seq? rule) (let [[afn src] rule] (apply-rule world cell afn src))))
+  ([world cell rule source]
     (let [result (apply rule (list cell world))]
       (cond
         (and result source) (merge result {:rule source})
         true result))))
 
+
 (defn- apply-rules
   "Derive a cell from this `cell` of this `world` by applying these `rules`."
   [world cell rules]
@@ -53,6 +78,7 @@
            (cond result result
              true (apply-rules world cell (rest rules))))))
 
+
 (defn- transform-cell
   "Derive a cell from this `cell` of this `world` by applying these `rules`. If an
    exception is thrown, cache its message on the cell and set it's state to error"
@@ -67,13 +93,16 @@
                            (.getMessage e)
                            (:generation cell)
                            (:state cell))
+                   :stacktrace (map #(.toString %) (.getStackTrace e))
                    :state :error}))))
 
+
 (defn transform-world
   "Return a world derived from this `world` by applying these `rules` to each cell."
   [world rules]
   (map-world world transform-cell (list rules)))
 
+
 (defn- transform-world-state
   "Consider this single argument as a map of `:world` and `:rules`; apply the rules
    to transform the world, and return a map of the new, transformed `:world` and
diff --git a/src/mw_engine/display.clj b/src/mw_engine/display.clj
index 0ad65e6..7dca8ff 100644
--- a/src/mw_engine/display.clj
+++ b/src/mw_engine/display.clj
@@ -1,22 +1,50 @@
-(ns mw-engine.display
-  (:use mw-engine.utils
-        mw-engine.world)
-  (:require [hiccup.core :refer [html]]))
+(ns ^{:doc "Simple functions to allow a world to be visualised."
+      :author "Simon Brooke"}
+  mw-engine.display
+  (:require [hiccup.core :refer [html]]
+            mw-engine.utils
+            mw-engine.world))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; mw-engine: the state/transition engine of MicroWorld.
+;;;;
+;;;; This program is free software; you can redistribute it and/or
+;;;; modify it under the terms of the GNU General Public License
+;;;; as published by the Free Software Foundation; either version 2
+;;;; of the License, or (at your option) any later version.
+;;;;
+;;;; This program is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;;; GNU General Public License for more details.
+;;;;
+;;;; You should have received a copy of the GNU General Public License
+;;;; along with this program; if not, write to the Free Software
+;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+;;;; USA.
+;;;;
+;;;; Copyright (C) 2014 Simon Brooke
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (defn format-css-class [state]
   "Format this `state`, assumed to be a keyword indicating a state in the
    world, into a CSS class"
   (subs (str state) 1))
 
+
 (defn format-image-path
   "Render this `state`, assumed to be a keyword indicating a state in the
    world, into a path which should recover the corresponding image file."
   [state]
   (format "img/tiles/%s.png" (format-css-class state)))
 
+
 (defn format-mouseover [cell]
   (str cell))
 
+
 (defn render-cell
   "Render this world cell as a Hiccup table cell."
   [cell]
@@ -25,11 +53,13 @@
      [:a {:href (format "inspect?x=%d&y=%d" (:x cell) (:y cell))}
       [:img {:alt (:state cell) :width 32 :height 32 :src (format-image-path state)}]]]))
 
+
 (defn render-world-row
   "Render this world `row` as a Hiccup table row."
   [row]
   (apply vector (cons :tr (map render-cell row))))
 
+
 (defn render-world-table
   "Render this `world` as a Hiccup table."
   [world]
diff --git a/src/mw_engine/drainage.clj b/src/mw_engine/drainage.clj
index 925b1a0..87a7207 100644
--- a/src/mw_engine/drainage.clj
+++ b/src/mw_engine/drainage.clj
@@ -1,11 +1,37 @@
-;; Experimental, probably of no interest to anyone else; attempt to compute drainage on a world,
-;; assumed to have altitudes already set from a heighmap.
+(ns ^{:doc "Experimental, probably of no interest to anyone else; attempt to
+      compute drainage on a world, assumed to have altitudes already set
+      from a heightmap."
+      :author "Simon Brooke"}
+  mw-engine.drainage
+  (:require [mw-engine.core :refer [run-world]]
+            [mw-engine.heightmap :as heightmap]
+            [mw-engine.utils :refer [get-int-or-zero get-least-cell get-neighbours
+                                     get-neighbours-with-property-value
+                                     map-world]]))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; mw-engine: the state/transition engine of MicroWorld.
+;;;;
+;;;; This program is free software; you can redistribute it and/or
+;;;; modify it under the terms of the GNU General Public License
+;;;; as published by the Free Software Foundation; either version 2
+;;;; of the License, or (at your option) any later version.
+;;;;
+;;;; This program is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;;; GNU General Public License for more details.
+;;;;
+;;;; You should have received a copy of the GNU General Public License
+;;;; along with this program; if not, write to the Free Software
+;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+;;;; USA.
+;;;;
+;;;; Copyright (C) 2014 Simon Brooke
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
-(ns mw-engine.drainage
-  (:use mw-engine.utils
-        mw-engine.world
-        mw-engine.core)
-  (:require [mw-engine.heightmap :as heightmap]))
 
 (def ^:dynamic *sealevel* 10)
 
@@ -18,37 +44,40 @@
   [world]
   (map-world world (fn [world cell] (merge cell {:rainfall 1}))))
 
+
 (defn flow-contributors
   "Return a list of the cells in this `world` which are higher than this
-  `cell` and for which this cell is the lowest neighbour, or which are at the 
+  `cell` and for which this cell is the lowest neighbour, or which are at the
    same altitude and have greater flow"
   [cell world]
   (filter #(map? %)
           (map
             (fn [n]
-              (cond 
+              (cond
                 (= cell (get-least-cell (get-neighbours world n) :altitude)) n
                 (and (= (:altitude cell) (:altitude n))
                      (> (or (:flow n) 0) (or (:flow cell) 0))) n))
-            (get-neighbours-with-property-value 
+            (get-neighbours-with-property-value
               world (:x cell) (:y cell) 1 :altitude
               (or (:altitude cell) 0) >=))))
 
+
 (defn is-hollow
-  "Detects point hollows - that is, individual cells all of whose neighbours 
-   are higher. Return true if this `cell` has an altitude lower than any of 
-   its neighbours in this `world`" 
+  "Detects point hollows - that is, individual cells all of whose neighbours
+   are higher. Return true if this `cell` has an altitude lower than any of
+   its neighbours in this `world`"
   [world cell]
   ;; quicker to count the elements of the list and compare equality of numbers
   ;; than recursive equality check on members, I think. But worth benchmarking.
   (let [neighbours (get-neighbours world cell)
         altitude (get-int-or-zero cell :altitude)]
     (= (count neighbours)
-       (count (get-neighbours-with-property-value 
+       (count (get-neighbours-with-property-value
                 world (:x cell) (:y cell) 1 :altitude altitude >)))))
 
+
 (defn flood-hollow
-  "Raise the altitude of a copy of this `cell` of this `world` to the altitude  
+  "Raise the altitude of a copy of this `cell` of this `world` to the altitude
    of the lowest of its `neighbours`."
   ([world cell neighbours]
     (let [lowest (get-least-cell neighbours :altitude)]
@@ -56,30 +85,33 @@
   ([world cell]
     (flood-hollow world cell (get-neighbours world cell))))
 
-(defn flood-hollows 
+
+(defn flood-hollows
   "Flood all local hollows in this `world`. At this stage only floods single
    cell hollows."
   [world]
-  (map-world world 
+  (map-world world
              #(if (is-hollow %1 %2) (flood-hollow %1 %2) %2)))
 
+
 (def max-altitude 255)
 
 (defn flow-nr
-  "Experimental non recursive flow algorithm, needs to be run on a world as 
+  "Experimental non recursive flow algorithm, needs to be run on a world as
    many times as there are distinct altitude values. This algorithm works only
    if applied sequentially from the highest altitude to the lowest, see
    `flow-world-nr`."
   [cell world]
   (if (= (- max-altitude (get-int-or-zero cell :generation))
          (get-int-or-zero cell :altitude))
-    (merge cell 
-           {:flow (reduce + 
-                          (map 
+    (merge cell
+           {:flow (reduce +
+                          (map
                             #(+ (get-int-or-zero % :rainfall)
                                 (get-int-or-zero % :flow))
                             (flow-contributors cell world)))})))
 
+
 (def flow
   "Compute the total flow upstream of this `cell` in this `world`, and return a cell identical
   to this one but having a value of its flow property set from that computation. The function is
@@ -99,6 +131,7 @@
                               (map (fn [neighbour] (:flow (flow neighbour world)))
                                    (flow-contributors cell world))))})))))
 
+
 (defn flow-world-nr
   "Experimental non-recursive flow-world algorithm"
   [world]
@@ -110,8 +143,9 @@
   [world]
   (map-world (rain-world world) flow))
 
+
 (defn run-drainage
   [hmap]
-  "Create a world from the heightmap `hmap`, rain on it, and then compute river 
+  "Create a world from the heightmap `hmap`, rain on it, and then compute river
    flows."
   (flow-world (rain-world (flood-hollows (heightmap/apply-heightmap hmap)))))
diff --git a/src/mw_engine/heightmap.clj b/src/mw_engine/heightmap.clj
index 403cad0..3ef8e3c 100644
--- a/src/mw_engine/heightmap.clj
+++ b/src/mw_engine/heightmap.clj
@@ -1,15 +1,39 @@
-;; Functions to apply a heightmap to a world.
-;;
-;; Heightmaps are considered only as greyscale images, so colour is redundent (will be
-;; ignored). Darker shades are higher.
-
-(ns mw-engine.heightmap
+(ns ^{:doc "Functions to apply a heightmap to a world."
+      :author "Simon Brooke"}
+  mw-engine.heightmap
   (:import [java.awt.image BufferedImage])
-  (:use mw-engine.utils
-        mw-engine.world)
-  (:require [fivetonine.collage.util :as collage :only [load-image]]
-            [mikera.image.core :as imagez :only [filter-image get-pixels]]
-            [mikera.image.filters :as filters]))
+  (:require [mikera.image.core :as imagez :only [filter-image get-pixels]]
+            [mikera.image.filters :as filters]
+            [mw-engine.utils :refer [abs get-int get-neighbours map-world]]
+            [mw-engine.world :refer [make-world]]))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; mw-engine: the state/transition engine of MicroWorld.
+;;;;
+;;;; This program is free software; you can redistribute it and/or
+;;;; modify it under the terms of the GNU General Public License
+;;;; as published by the Free Software Foundation; either version 2
+;;;; of the License, or (at your option) any later version.
+;;;;
+;;;; This program is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;;; GNU General Public License for more details.
+;;;;
+;;;; You should have received a copy of the GNU General Public License
+;;;; along with this program; if not, write to the Free Software
+;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+;;;; USA.
+;;;;
+;;;; Copyright (C) 2014 Simon Brooke
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; Heightmaps are considered only as greyscale images, so colour is redundent
+;;;; (will be ignored). Darker shades are higher.
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 
 (defn tag-property
@@ -35,6 +59,7 @@
                         (get-int cell :x)
                         (get-int cell :y)) 256))))})))
 
+
 (defn tag-gradient
   "Set the `gradient` property of this `cell` of this `world` to the difference in
    altitude between its highest and lowest neghbours."
@@ -47,12 +72,14 @@
         gradient (- highest lowest)]
     (merge cell {:gradient gradient})))
 
+
 (defn tag-gradients
   "Set the `gradient` property of each cell in this `world` to the difference in
    altitude between its highest and lowest neghbours."
   [world]
   (map-world world tag-gradient))
 
+
 (defn tag-altitude
   "Set the altitude of this cell from the corresponding pixel of this heightmap.
    If the heightmap you supply is smaller than the world, this will break.
@@ -67,6 +94,7 @@
   ([cell heightmap]
     (tag-property cell :altitude heightmap)))
 
+
 (defn apply-heightmap
   "Apply the image file loaded from this path to this world, and return a world whose
   altitudes are modified (added to) by the altitudes in the heightmap. It is assumed that
@@ -78,20 +106,21 @@
   * `imagepath` a file path or URL which indicates an (ideally greyscale) image file."
   ([world imagepath]
     (let [heightmap (imagez/filter-image
-                      (filters/grayscale)
-                      (collage/load-image imagepath))]
+                      (imagez/load-image imagepath)
+                      (filters/grayscale))]
       (map-world
         (map-world world tag-altitude (list heightmap))
         tag-gradient)))
    ([imagepath]
     (let [heightmap (imagez/filter-image
-                      (filters/grayscale)
-                      (collage/load-image imagepath))
+                      (imagez/load-image imagepath)
+                      (filters/grayscale))
           world (make-world (.getWidth heightmap) (.getHeight heightmap))]
       (map-world
         (map-world world tag-altitude (list heightmap))
         tag-gradient))))
 
+
 (defn apply-valuemap
   "Generalised from apply-heightmap, set an arbitrary property on each cell
    of this `world` from the values in this (ideally greyscale) heightmap.
@@ -102,6 +131,6 @@
       intensity of the corresponding cell of the image."
   [world imagepath property]
     (let [heightmap (imagez/filter-image
-                      (filters/grayscale)
-                      (collage/load-image imagepath))]
+                      (imagez/load-image imagepath)
+                      (filters/grayscale))]
       (map-world world tag-property (list property heightmap))))
diff --git a/src/mw_engine/natural_rules.clj b/src/mw_engine/natural_rules.clj
index 6032ca3..af4a124 100644
--- a/src/mw_engine/natural_rules.clj
+++ b/src/mw_engine/natural_rules.clj
@@ -1,26 +1,56 @@
-;; A set of MicroWorld rules describing a simplified natural ecosystem.
-;;
-;; Since the completion of the rule language this is more or less obsolete - 
-;; there are still a few things that you can do with rules written in Clojure
-;; that you can't do in the rule language, but not many and I doubt they're
-;; important.
-
-(ns mw-engine.natural-rules
-  (:use mw-engine.utils
+(ns ^{:doc "A set of MicroWorld rules describing a simplified natural ecosystem."
+       :author "Simon Brooke"}
+  mw-engine.natural-rules
+  (:require mw-engine.utils
         mw-engine.world))
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; mw-engine: the state/transition engine of MicroWorld.
+;;;;
+;;;; This program is free software; you can redistribute it and/or
+;;;; modify it under the terms of the GNU General Public License
+;;;; as published by the Free Software Foundation; either version 2
+;;;; of the License, or (at your option) any later version.
+;;;;
+;;;; This program is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;;; GNU General Public License for more details.
+;;;;
+;;;; You should have received a copy of the GNU General Public License
+;;;; along with this program; if not, write to the Free Software
+;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+;;;; USA.
+;;;;
+;;;; Copyright (C) 2014 Simon Brooke
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; Since the completion of the rule language this is more or less obsolete -
+;;;; there are still a few things that you can do with rules written in Clojure
+;;;; that you can't do in the rule language, but not many and I doubt they're
+;;;; important.
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+
 ;; treeline at arbitrary altitude.
 (def treeline 150)
 
+
 ;; waterline also at arbitrary altitude.
 (def waterline 10)
 
+
 ;; and finally snowline is also arbitrary.
 (def snowline 200)
 
+
 ;; Rare chance of lightning strikes
 (def lightning-probability 500)
 
+
 ;; rules describing vegetation
 (def vegetation-rules
   (list
@@ -72,8 +102,8 @@
     ;; Forest increases soil fertility
     (fn [cell world]
       (cond (member? (:state cell) '(:forest :climax))
-        (merge cell {:fertility (+ (get-int cell :fertility) 1)})))
-  ))
+        (merge cell {:fertility (+ (get-int cell :fertility) 1)})))))
+
 
 ;; rules describing herbivore behaviour
 (def herbivore-rules
@@ -139,8 +169,8 @@
     (fn [cell world]
       (cond
         (>= (get-int cell :wolves) 2)
-        (merge cell {:wolves (int (* (:wolves cell) 2))})))
-    ))
+        (merge cell {:wolves (int (* (:wolves cell) 2))})))))
+
 
   ;; rules which initialise the world
   (def init-rules
@@ -152,12 +182,11 @@
      (fn [cell world]
        (cond (and (= (:state cell) :new) (> (get-int cell :altitude) snowline)) (merge cell {:state :snow})))
      ;; in between, we have a wasteland.
-     (fn [cell world] (cond (= (:state cell) :new) (merge cell {:state :grassland}))
-     )))
+     (fn [cell world] (cond (= (:state cell) :new) (merge cell {:state :grassland})))))
+
 
 (def natural-rules (flatten
                     (list
                      vegetation-rules
                      herbivore-rules
-                     ;; predator-rules
-                     )))
+                     predator-rules)))
diff --git a/src/mw_engine/utils.clj b/src/mw_engine/utils.clj
index 279ec18..53c359f 100644
--- a/src/mw_engine/utils.clj
+++ b/src/mw_engine/utils.clj
@@ -1,11 +1,33 @@
-;; Utility functions needed by MicroWorld and, specifically, in the
-;; interpretation of MicroWorld rule.
-
-(ns mw-engine.utils
+(ns ^{:doc " Utility functions needed by MicroWorld and, specifically, in the
+      interpretation of MicroWorld rule."
+      :author "Simon Brooke"}
+  mw-engine.utils
   (:require
-;;    [clojure.core.reducers :as r]
     [clojure.math.combinatorics :as combo]))
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; mw-engine: the state/transition engine of MicroWorld.
+;;;;
+;;;; This program is free software; you can redistribute it and/or
+;;;; modify it under the terms of the GNU General Public License
+;;;; as published by the Free Software Foundation; either version 2
+;;;; of the License, or (at your option) any later version.
+;;;;
+;;;; This program is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;;; GNU General Public License for more details.
+;;;;
+;;;; You should have received a copy of the GNU General Public License
+;;;; along with this program; if not, write to the Free Software
+;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+;;;; USA.
+;;;;
+;;;; Copyright (C) 2014 Simon Brooke
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
 (defn abs
   "Surprisingly, Clojure doesn't seem to have an abs function, or else I've
    missed it. So here's one of my own. Maps natural numbers onto themselves,
@@ -16,10 +38,12 @@
   [n]
   (if (neg? n) (- 0 n) n))
 
+
 (defn member?
   "True if elt is a member of col."
   [elt col] (some #(= elt %) col))
 
+
 (defn get-int-or-zero
   "Return the value of this `property` from this `map` if it is a integer;
    otherwise return zero."
@@ -27,6 +51,7 @@
   (let [value (map property)]
     (if (integer? value) value 0)))
 
+
 (defn init-generation
   "Return a cell like this `cell`, but having a value for :generation, zero if
    the cell passed had no integer value for generation, otherwise the value
@@ -46,8 +71,9 @@
   [world x y]
   (and (>= x 0)(>= y 0)(< y (count world))(< x (count (first world)))))
 
+
 (defn map-world-n-n
-  "Wholly non-parallel map world implementation"
+  "Wholly non-parallel map world implementation; see documentation for `map-world`."
   ([world function]
     (map-world-n-n world function nil))
   ([world function additional-args]
@@ -59,8 +85,9 @@
                              row)))
                   world))))
 
+
 (defn map-world-p-p
-  "Wholly parallel map world implementation"
+  "Wholly parallel map-world implementation; see documentation for `map-world`."
   ([world function]
     (map-world-p-p world function nil))
   ([world function additional-args]
@@ -91,6 +118,7 @@
                              row)))
                   world))))
 
+
 (defn get-cell
   "Return the cell a x, y in this world, if any.
 
@@ -101,6 +129,7 @@
   (cond (in-bounds world x y)
     (nth (nth world y) x)))
 
+
 (defn get-int
   "Get the value of a property expected to be an integer from a map; if not present (or not an integer) return 0.
 
@@ -113,6 +142,7 @@
             true 0))
         true (throw (Exception. "No map passed?"))))
 
+
 (defn population
   "Return the population of this species in this cell. Currently a synonym for
    `get-int`, but may not always be (depending whether species are later
@@ -123,6 +153,7 @@
   [cell species]
   (get-int cell species))
 
+
 (def memo-get-neighbours
   "Memoised get neighbours is more efficient when running deeply recursive
    algorithms on the same world. But it's less efficient when running the
@@ -137,6 +168,7 @@
                             (range (- x depth) (+ x depth 1))
                             (range (- y depth) (+ y depth 1)))))))))
 
+
 (defn get-neighbours
     "Get the neighbours to distance depth of a cell in this world.
 
@@ -170,6 +202,7 @@
     ([world cell]
       (get-neighbours world cell 1)))
 
+
 (defn get-neighbours-with-property-value
   "Get the neighbours to distance depth of the cell at x, y in this world which
    have this value for this property.
@@ -215,6 +248,7 @@
   ([world cell state]
     (get-neighbours-with-state world cell 1 state)))
 
+
 (defn get-least-cell
   "Return the cell from among these `cells` which has the lowest numeric value
   for this `property`; if the property is absent or not a number, use this
@@ -242,6 +276,7 @@
     true
     cell))
 
+
 (defn set-property
   "Return a world like this `world` but with the value of exactly one `property`
    of one `cell` changed to this `value`"
@@ -258,6 +293,7 @@
                  row)))
         world))))
 
+
 (defn merge-cell
   "Return a world like this `world`, but merge the values from this `cell` with
    those from the cell in the world with the same co-ordinates"
diff --git a/src/mw_engine/version.clj b/src/mw_engine/version.clj
deleted file mode 100644
index d3fa41d..0000000
--- a/src/mw_engine/version.clj
+++ /dev/null
@@ -1,16 +0,0 @@
-(ns mw-engine.version
-  (:gen-class))
-
-(defn get-implementation-version 
-  "Get the implementation version from the package of this namespace, which must
-   be compiled into a class (see clojure.java.interop). See 
-   http://stackoverflow.com/questions/12599889/how-to-get-runtime-access-to-version-number-of-a-running-clojure-application
-   TODO: doesn't work yet."
-  []
-  (try 
-    (.getImplementationVersion (.getPackage (eval 'mw-engine.version)))
-    (catch Exception any "Unknown")
-    ))
-
-(defn -main []
-  (get-implementation-version ))
diff --git a/src/mw_engine/world.clj b/src/mw_engine/world.clj
index 2aa515f..9001ed6 100644
--- a/src/mw_engine/world.clj
+++ b/src/mw_engine/world.clj
@@ -1,15 +1,43 @@
-;; Functions to create and to print two dimensional cellular automata. Nothing in this
-;; file should determine what states are possible within the automaton, except for the
-;; initial state, :new.
-;;
-;; A cell is a map containing at least values for the keys :x, :y, and :state.
-;;
-;; A world is a two dimensional matrix (sequence of sequences) of cells, such
-;; that every cell's :x and :y properties reflect its place in the matrix.
+(ns ^{:doc "Functions to create and to print two dimensional cellular automata."
+       :author "Simon Brooke"}
+  mw-engine.world
+	(:require [clojure.string :as string :only [join]]
+            [mw-engine.utils :refer [population]]))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; mw-engine: the state/transition engine of MicroWorld.
+;;;;
+;;;; This program is free software; you can redistribute it and/or
+;;;; modify it under the terms of the GNU General Public License
+;;;; as published by the Free Software Foundation; either version 2
+;;;; of the License, or (at your option) any later version.
+;;;;
+;;;; This program is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;;; GNU General Public License for more details.
+;;;;
+;;;; You should have received a copy of the GNU General Public License
+;;;; along with this program; if not, write to the Free Software
+;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+;;;; USA.
+;;;;
+;;;; Copyright (C) 2014 Simon Brooke
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; Functions to create and to print two dimensional cellular automata.
+;;;; Nothing in this namespace should determine what states are possible within
+;;;; the automaton, except for the initial state, :new.
+;;;;
+;;;; A cell is a map containing at least values for the keys :x, :y, and :state.
+;;;;
+;;;; A world is a two dimensional matrix (sequence of sequences) of cells, such
+;;;; that every cell's :x and :y properties reflect its place in the matrix.
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
-(ns mw-engine.world
-  (:use mw-engine.utils)
-	(:require [clojure.string :as string :only [join]]))
 
 (defn- make-cell
   "Create a minimal default cell at x, y
@@ -19,6 +47,7 @@
   [x y]
   {:x x :y y :state :new})
 
+
 (defn- make-world-row
   "Make the (remaining) cells in a row at this height in a world of this width.
 
@@ -30,6 +59,7 @@
     true (cons (make-cell index height)
                (make-world-row (inc index) width height))))
 
+
 (defn- make-world-rows
   "Make the (remaining) rows in a world of this width and height, from this
    index.
@@ -51,6 +81,7 @@
   [width height]
   (apply vector (make-world-rows 0 width height)))
 
+
 (defn truncate-state
   "Truncate the print name of the state of this cell to at most limit characters."
   [cell limit]
@@ -58,6 +89,7 @@
     (cond (> (count (str s)) limit) (subs s 0 limit)
       true s)))
 
+
 (defn format-cell
   "Return a formatted string summarising the current state of this cell."
   [cell]
@@ -66,11 +98,13 @@
           (population cell :deer)
           (population cell :wolves)))
 
+
 (defn- format-world-row
   "Format one row in the state of a world for printing."
   [row]
   (string/join (map format-cell row)))
 
+
 (defn print-world
   "Print the current state of this world, and return nil.
 
diff --git a/test/mw_engine/heightmap_test.clj b/test/mw_engine/heightmap_test.clj
index 23f63fa..66207a4 100644
--- a/test/mw_engine/heightmap_test.clj
+++ b/test/mw_engine/heightmap_test.clj
@@ -7,7 +7,7 @@
 
 (deftest apply-heightmap-test
   (testing "Heightmap functionality"
-           (let [world (apply-heightmap (as-file "resources/heightmaps/test9x9.png"))
+           (let [world (apply-heightmap "resources/heightmaps/test9x9.png")
                  altitudes (map #(:altitude %) (flatten world))
                  gradients (map #(:gradient %) (flatten world))]
              (is (= (count world) 9) "World should be 9x9")
@@ -22,7 +22,7 @@
              (is (> (apply + gradients) 0)
                  "At least some gradients must be positive, none should be negative"))
            ;; alternate means of making the world, same tests.
-           (let [world (apply-heightmap (world/make-world 9 9) (as-file "resources/heightmaps/test9x9.png"))
+           (let [world (apply-heightmap (world/make-world 9 9) "resources/heightmaps/test9x9.png")
                  altitudes (map #(:altitude %) (flatten world))
                  gradients (map #(:gradient %) (flatten world))]
              (is (= (count world) 9) "World should be 9x9")
@@ -42,7 +42,7 @@
 
 (deftest apply-valuemap-test
   (testing "Valuemap functionality"
-    (let [image (as-file "resources/heightmaps/test9x9.png")
+    (let [image "resources/heightmaps/test9x9.png"
           world (apply-valuemap (apply-heightmap image) image :arbitrary)
           altitudes (map #(:altitude %) (flatten world))
           arbitraries (map #(:arbitrary %) (flatten world))]