Keep lock while doing recycle_buffer
Pass context to main loop
Recycle WorkItems in a free list
Push and pull from the node data loop
Do async start/pause in alsa
Add alsa fds right after open.
Remove unused events, drained and marker can be done with
ASYNC_COMPLETED messages
Handle result of idle callback to disable the poll item
Identify poll items with a unique id.
Remove set_state vfunc
push_event -> send_command, commands are to do something, events are the
result of something.
Add poll item in v4l2 as soon as we have the fd but disable the item
until streaming starts.
Make a main-loop object with associated helper functions to handle async
methods.
rtloop -> data_loop
Handle async results a lot better.
Remove REMOVE_MEM command. We don't need it.
Handle stream memory updates better.
