[ioquake3] VoIP support for ioquake3...

[Ryan C. Gordon]

> - Fill in the mixer code for S_Base_RawSamples() where stream != 0 (or 
> are we only OpenAL now?).

This is implemented in the latest patch in Bugzilla now, so you can hear 
incoming VoIP transmissions even if you aren't using OpenAL.

There's still no audio capture support for non-OpenAL clients, and I 
don't plan to add it. SDL 1.3 will provide a cross-platform API for 
this, but it's not available yet, and I don't plan to write 
Windows/Mac/ALSA/OSS/blahblahblah codepaths in the meantime. Just use 
OpenAL.

--ryan.