channel mixers was broken (again) in 0.8.1 and 0.8.2; hopefully this
  will fix it for good, by allowing audio filters to request a specific
  format rather than imposing them an arbitrary one
- various other small fixes in the audio output core
- option to force detection of Dolby Surround
- simple module to decode Dolby Surround
- increase spatialization with two center speakers and fix channel
  order for 7.1 streams in the headphone channel mixer