Fix XCode build, fixes #101
Some fixes for the tty client
Use NullAudio for the TTY client
Fix the build
Don't link OpenAL into tty client and don't include NullAudio in dedicated server
Properly handle www downloads being interrupted by a disconnect
Add preset for hw such as Intel GMA 3xxx/4xxx
Fix bound check in SetReverb
Make CvarSystem use auto& to iterate over cvars

Also do some cosmetic changes (docs, ...)
Fix cvars not being reset properly when sv_cheats is set to 0