Moved the rendering code out to a separate directory in the hope that it can someday be completely decoupled from the rest of the library and be expanded to an awesome 2D on 3D library.

--HG--
rename : src/video/windows/SDL_d3drender.c => src/render/direct3d/SDL_d3drender.c
rename : src/video/SDL_renderer_gl.c => src/render/opengl/SDL_renderer_gl.c
rename : src/video/SDL_renderer_gles.c => src/render/opengles/SDL_renderer_gles.c
rename : src/video/SDL_renderer_sw.c => src/render/software/SDL_renderer_sw.c

src/events/SDL_events.c

@@ -116,8 +116,6 @@ SDL_StopEventLoop(void)
 int
 SDL_StartEventLoop(void)
 {
-    int retcode;
-
     /* Clean out the event queue */
     SDL_EventQ.lock = NULL;
     SDL_StopEventLoop();