Summary: SDL graphics drawing primitives and other support functions

Description:
The SDL_gfx library evolved out of the SDL_gfxPrimitives code.

The current components of the SDL_gfx library are:
- Graphic Primitives (SDL_gfxPrimitves.h)
- Rotozoomer (SDL_rotozoom.h)
- Framerate control (SDL_framerate.h)
- MMX image filters (SDL_imageFilter.h)

The library is backwards compatible to the above mentioned code. It's
is written in plain C and can be used in C++ code.

Maintainer: nobody