This included half the game state and lots of unneeded parts of the software renderer.
The two modules that are shared between softpoly and the classic software renderer have been moved to a neutral place.
- change SpriteDrawerArgs to draw a full sprite instead of one column at a time
- add r_noaccel cvar to allow forced software rendering of the psprites (useful for debugging and also one person on the forum actually requested this feature)
- remove FWallTmapVals and calculate texture coordinates directly from FWallCoords
- move portal clipping out of the inner sprite drawing loop
