Rename the source-output object to channel because it is used for both
input and output.
Start the beginnings of sink support. This will make it possible to make
pinos consume data as well as provide data.
Only go to READY in setup_pipeline, this is enough to get the caps. We
don't want to go to PAUSED yet because we don't want to negotiate a
format.
Mark the source busy after we configured the capsfilter so that we can
let the source negotiate correctly.
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.
