AE: fix hidden setting stereo upmix if spdif is selected
AE: allow channel BC to be mixed into BL/BR os SL/SR
ActiveAE: let sink do channel mapping for 7.1
AESinkAlsa: Use 51Wide and 71Wide Maps when we need to do so
ActiveAE: limit buffertime to 80ms
ActiveAE: fix incorrect return values of GetSpace
WASAPI: try other channels layouts on init if requested one is not supported
WASAPI: handle obsolete 7.1 wide layout
Merge pull request #3744 from FernetMenta/aefixes

Aefixes