Add connection message for PORT_COMMAND
Add rtkit support to ask for realtime priority
work on stream states and improve negotiation
Rework of port linking works, keep separate state for realtime threads
and use message passing to update the state.
Don't try to link nodes that are removed.
Open the device in the ALSA monitor to detect source or sink
Implement send_command as async methods on the plugins, use async
replies to sync start and stop.
Work on alsa sink.
Implement async PAUSE/START on v4l2 src. move the STREAMON/OFF calls to
the mainloop because they have high latency, add the poll descriptors
from the data loop.
Remove the memory stuff from the spa API, we can do thing more simple
and efficiently if we always allocate buffers outside of the plugins and
only implement an alloc function on the node when it can do something
clever.
Move serialize code to the props/format/buffer code
Make it possible to copy a format and properties.
Remove port added and port removed, we can get that info by inspecting
the port ids.
Remove data from ringbuffer, we just need the ringbuffer to keep track
of the read and write positions.
Handle async-complete in the main thread
Work on async node initialization
Work on using a queue as the link between nodes
Make the daemon link things based on the node states
Use queue helper in v4l2
