Stopping Camerabin

[Ian Davidson]

I am trying to use camerabin to take still pictures. All now goes well 
until I try to stop.

I can send a state change to camerabin to set the state to NULL - but I 
do not see anything telling me that the state change has worked.  
Consequently, the main loop is never exited, so the program hangs.

Should I be waiting for the main loop to see some message, so that it 
can exit - or should I just set the state to NULL, then unref the 
pipeline, remove the bus watch and unref the main loop?

Ian