Added SDL_RenderClear() as a fast method of clearing the screen to the drawing color. Renamed SDL_RenderPoint() and SDL_RenderLine() to SDL_RenderDrawPoint() and SDL_RenderDrawLine(). Added API for rectangle drawing (as opposed to filling) Added placeholder API functions for circles and ellipses ... I'm not sure whether these will stay. Optimized software line drawing quite a bit. Added support for Wu's anti-aliased line drawing, currently disabled by default.