In addition, linux builds (and ALSA/PA) now work again
Also renames "AudioThread" to "AudioBackend". The new name is more descriptive of what the class really is responsible for, since the backends are not responsible for managing the audio thread. NOTE: Right now only XAudio2 is supported
* Add a channel map to the PA backend to prevent issues with more than 6 channels * Arranged the mapping per cellAudio.cpp