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.
Send the base-time to the client so that it can calibrarte the clock.
Wait until we are completely negotiated before completing the state
change to paused. This makes it possible to provide a clock and decide
if we are live or not.
