(svn r2962) - const correctness for all Get* functions and most Draw* functions that don't change their pointer parameters
- change a lot of byte player types to PlayerID
- beautify header files, same "#endif /* filename */" ending

(svn r2866) Move all functions and tables which aren't directly involved in managing the sprite heap to a new file gfxinit.c.
This doesn't ease the global variable mess, but makes the distinction between sprite heap and gfx loading routines easier.