Add pw_buffer
Add queue/dequeue methods, remove old methods
Add get and set for properties
Update gst elements and examples
Update the API to work branch which is more future proof
The listeners are generally useful in spa, move it there and rename
to hooks. Implement loop hooks with it.
Fix some cleanup issues in stream and remote
Remove signals.
Rename callbacks -> events, use listeners to listen for events.
Callbacks are still used in spa for things you can listen to only
once.
