Replace Hsieh/FNV/Penn hash functions with City/Murmur3/Spooky.

Hsieh/FNV/Penn don't perform particularly well in the SMHasher suite of
tests (see https://code.google.com/p/smhasher/). The new hash functions
benchmark favorably in terms of speed and hashing characteristics such
as avalanching, uniformity, etc.

git-svn-id: https://pennmush.googlecode.com/svn/trunk@1760 ba372814-4f39-11de-9ad6-1127a62b9fcd