GeneralHash : support full 32-bit or 64-bit hash values

[lemire]

The current GeneralHash implementation supports 19-bit hash values, but nothing higher. It should be easy to support 32-bit or higher hash values.

http://www.wolframalpha.com/input/?i=factor+x^0+x^1+x^2+x^5+x^6+x^7+x^9+x^11+x^14+x^19+x^20+x^21+x^22+x^24+x^27+x^30+x^32+mod+2

c.c. @vcunat