Added audio conference support

Ignore-this: 8b38a75dcce819f2f0a3957b1cd7dda2

darcs-hash:20100312103821-1e3d8-3fbdddc6251389b0dd156ebfa6204b323c871ea7
Fixed mixer port

Ignore-this: 41b69da737e6f36497c4268e0a6c960d

darcs-hash:20100312180136-1e3d8-2a560a391192a8071641fab3a14e05564fbcf5d8