[Golly-test] fixed problem with hash() command

[Andrew T. <an...@tr...>]

I noticed recently that oscar.py was incorrectly reporting certain
patterns as periodic (eg. Patterns/Other-Rules/Turmites/AlienCounter.rle).
It turns out I was using a really dumb hash function for universes with
more than 2 states.  I think I've fixed this now, but let me know if
you see any problems using oscar.py with the new code.

I've factored out the hash function code into GSF_hash() in wxscript.cpp.
I didn't change the function for 2-state universes because I'm pretty
confident that works well (nobody has reported any problems for a long time).

Andrew