Add an option for a simpler virtual channel setup
Add an option for a simpler virtual channel setup

With HRTF mixing, certain things are mixed to virtual channels to be filtered
with HRTF later. This allows for using an 8-channel cube instead of a 14-
channel cube+diamond.

BeamNG/openal-soft,Wemersive/openal-soft,BeamNG/openal-soft,aaronmjacobs/openal-soft,arkana-fts/openal-soft,arkana-fts/openal-soft,alexxvk/openal-soft,irungentoo/openal-soft-tox,alexxvk/openal-soft,Wemersive/openal-soft,aaronmjacobs/openal-soft,irungentoo/openal-soft-tox