Now creating the correct internal bignum representation

add_integers returns an integer which by inspection of the internal representation is correct, but the print representation is not correct.

unit-tests/bignum.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+expected='1,152,921,504,606,846,976'
+# 1,152,921,504,606,846,975 is the largest single cell positive integer;
+# consequently 1,152,921,504,606,846,976 is the first two cell positive integer.
+actual=`echo '(+ 1,152,921,504,606,846,975 1)' | target/psse -v 68 2>bignum.log | tail -1`
+
+if [ "${expected}" = "${actual}" ]
+then
+    echo "OK"
+else
+    echo "Fail: expected '${expected}', got '${actual}'"
+    exit 1
+fi