Make it possible to assign an arbitary node as the port mixer.
Also remove dynamically added ports.
Improve negotiation and allocation on the mixer ports
Add some more SSE optimisations
Move float mixer from the audio dsp to the port
Remove pw_node_get_free_port() and do things more explicitly.
Handle mixer ports in client-node
Implement audioconvert as a complex element of fmtconver,
channelmix and resample.
Make copying resample just to test.
Plug the converter into pw_stream.
Separate buffer sizes in the info. Make it possible to not set
data pointers for when we use memfd for the memory.
Improve format conversion.
Work on in-place conversion in test-convert2
