using racket's read-bitmap instead of SDL_image's img-load
indentation fix
Adding an example to show something move based on mouse movement.  Also exposed a bitmap->sdl-surface function.
Oops on the rectangle dimensions
Changing sdl-blit-surface so it can take NULL as the source rectangle.
Merge pull request #3 from dyoo/no_sdl_image

Adding an example to show something move based on mouse movement.
Merge branch 'no_sdl_image' of https://github.com/pb82/sdl4racket into no_sdl_image
added a first unit test
Merge branch 'no_sdl_image'
using only atomic mallocs and safe cvectors