New PPU stuff on the way. Still subject to changes.
* faster tile drawing
* new GPU code although not finished (not as fast as I'd wish and prone to freezes)
* master brightness
* sprites with Y<0 now show up (although that seems to cause some issues (SMW: leftover 16x16 sprites with Y=-15))
* get rid of useless size parameter in MemFree()
* more shit I forgot