Add more buffer types to add and remove memory shared memory between the
server and client. We would like to send buffers only once and then
simply reference them by index.
Do format negotiation and stream start with a START message.
Bring back the channel object. Making a node and port on the client side
was rather awkward because of the async nature of many methods. It feels
better to have a specific communication channel object to interface with
a server side port.
Use port activate/deactivate to start/stop streams
Remove links from the ports. We let other objects install a callback on
the port to receive and route buffers.
Add refcounting to buffers.
Use static memory on ports for buffer input and output memory.
Improve negotiation, let format and properties be negotiated on ports as
the data passes.
Improve some debug info.
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.
