Added :save-initial-population argument, defaluts to false; calc tweaks.
Adds stack trace printing on exceptions.
Added printing of exception to stdout.
Fixes ULTRA arithmetic error, and also prints exception stack traces to both stdout and stderr.
thelmuth/print-stack-trace-on-error
version bump
Made random code inserted with ULTRA mutation come from random-code function.
thelmuth/fix-rand-code-in-ultra