Make special format types for planar and interleaved instead of
having a field.
Add enum for audio channel positions
Add some default audio channel layouts
Place the channel layout in the audio format when possible
alsa: place audio channel positions in format
Add sse optimized channel mixing for some common cases
Remove name from port info, it's not mandatory and in the properties
Add direction to port info
Implement audioconvert as a complex element of fmtconver,
channelmix and resample.
Make copying resample just to test.
Plug the converter into pw_stream.
