Fix a bug where Disobedience wouldn't always notice that a track had

Fix a bug where Disobedience wouldn't always notice that a track had
started playing.  If you turn off random play, then either scratch or
wait for the current track, then turn random play on again then it
would not notice the new track.

The reason is that random track choice is now asynchronous to start a
new track and Disobedience wasn't listening for "playing" log
messages.  Now it does.