[racket] a libSDL (1.2) binding for Racket

Hello,

there does not seem to be a libSDL (1.2) binding for Racket, so i made 
one. libSDL (simple direct media layer) is a popular C library to 
interface with video and audio devices and to handle input events. It's 
mostly used for games.

The binding is not complete but a reasonable part of video and event 
handling is already working. If you're interested, have a look at:

     https://github.com/pb82/sdl4racket

I'm new to Racket and to lisp-like languages in general, so the code may 
not be that good. But i'm open to suggestions and critique.

Peter