Removed atexit() from most of the test programs; atexit(SDL_Quit) isn't safe if SDL is built with a non-cdecl calling convention, and it's just generally bad practice anyhow. Now programs explicitly call SDL_Quit() where appropriate, wrap SDL_Quit() in a cdecl function where it can't be avoided, and rely on the parachute where a crash might have hit the atexit() before (these ARE test programs, after all!).