Hash cluts rather than using the address

This significantly improves Final Fantasy Tactics, which no longer has major graphical glitches or huge slowdowns.

Probably could be done better - assuming e.g. the clutload instruction is only done so often, etc.  Also, I had to use CityHash32 on the (usually not large) clut, because with any simple checksum I was getting bad colors sometimes.  It seems to be fairly fast.

Also includes a small performance improvement for 4-bit textures.

-[Unknown]