Some old 2D games change palettes very frequently, which causes the
texture to be updated for each render.
This change uses a hash of the palette to detect changes, and include
the palette type in the cache key to distinguish textures of different
depth.
Paletted textures using a 32-bit palette and YUV textures are now
converted to 8888 format, which results in a lossless conversion.
Fixes background texture quality in Alone in the Dark.
Flyinghead