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.
Make an object for a processing node.
Implement a sink node. Make it possible to implement Sink and Source
interfaces to provide input/output from the node.
Improve pinosdepay to track fds and handle format changes.
