Make a property to limit the number of peers on a port. By default we can
link an output port multiple times (with the same format) but we can only
link to an input port once (else we would have to do mixing).
Use a pointer array to keep track of peers
Add autoconnect property to the ports
Remove the upload-node, clients that want to upload media just create a
node with an (unconnected) output port. Other clients can then connect
to this new output port.
Copy formats on newly linked ports.
Remove the client object, it is not very useful now that we have the
nodes.
Fix some properties on the proxy objects.
Use sendmsg and recvmsg directly because the GIO ones do allocations.
make pinos_properties_merge and use it to combine properties from nodes
and ports.
Add buffer flags. The idea is to make it possible to easily check when a
buffer contains control information that we need to parse to update the
port fields.
Make the client create remote nodes and ports and set up proxies for
them.
Make a port base class implementing most of the logic to pass buffers
locally and remotely.
Remove most code from stream.c, it's now in the port.
Make a portsink and portsrc that can write and read to/from any port. We
use these in the server to send and receive data.
Rework format negotiation. The final format is now sent in-line before
the data. The server will select a format on output ports.
