[SDL] More keys hold down at once problem.

[Ryan C. Gordon]

> It looks and runs great, but I'm having problems with multiple players, 
> when there are 4 players pushing down keys all at once. If there are 
> more then 3 to 5 keys down or something like that then the rest of the 
> keypresses aren't recieved by the game. This is a real big hit on the 
> playablity and I hoped someone knows how to solve this. (easiest way to 
> test this is holding down UHJK keys and then try to play with the WASD 
> keys)

This isn't an SDL bug, it's a hardware issue; most keyboards don't let 
you hold down more than X keys at once without losing some of the input.

--ryan.