Replace the AsyncDone event with an explicit done callback in the node
to signal completion of an async operation.
Pass read and write fd together with the transport
Move the proxy plugin to the client-node
Move serialization code to pinos because its specific to pinos
Move some functions to the .h files
Make the mapper dynamic
We now only allow per port preallocated buffers. We exchange the index
into the array instead of passing the buffers around. We still use the
refcount to track when a buffer can be reused.
Improve API a little, allow passing the node as the first argument of
the interface call.
Implement alloc_buffer in v4l2 and improve the test.
