[SDL] SDL mouse events.

[Lucas]

> Thanks, that did the job.
>
> At 5Fps, I get 96-102 mouse events when moving the mouse, meaning a razor 
> mouse would fill the queue.
> I don't understand why key events did queue up properly without 
> SDL_PumpEvents() as I read it they shouldn't.
> Windows XP btw.

Also, my mouse only has a 500Hz sample rate(just checked it and it seems 
consistent with the 96-102 at 5fps).
1000Hz is quite common under FPS gamers.