Changes:
Implement software surround downmixing (fix#796).
Fix a crash when no audio renderer were created when stopping emulation.
NOTE: This PR also disable support of 5.1 surround on the OpenAL backend as we cannot detect if the hardware directly support it. (the downmixing applied by OpenAL on Windows is terribly slow)
* Partial voice implementation on audio renderer
* Implemented audren resampler (based on original impl)
* Fix BiquadFilter struct
* Pause audio playback on last stream buffer
* Split audren/audout files into separate folders, some minor cleanup
* Use AudioRendererParameter on GetWorkBufferSize aswell
* Bump audren version to REV4, name a few things, increase sample buffer size
* Remove useless new lines
Mary
gdkchan