Complete reworking of the REPL

which is good in itself, but not what I was meant to be working on.

unit-tests/eval-integer.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 expected='5'
-actual=`echo "(eval 5)" | target/psse 2> /dev/null | head -2 | tail -1`
+actual=`echo "(eval 5)" | target/psse | tail -1`
 
 if [ "${expected}" = "${actual}" ]
 then