audio: Add debug logging of stream switching
audio: Queue audio sink data to give us some headroom for about to finish events
core: Add a bunch of TODOs
audio: Add stream_changed event plus tests
audio: Slight test refactor to not hide what is going on
audio: Add more tests for audio events
audio: Add position_changed event to know when seeks happen
audio: Add about to finish callback support
audio: Debug log position_changed event triggering
audio: Update dummy audio used for testing
audio: Update tests and dummy audio actor to pass
audio: Add more TODOs
docs: Add Mopidy-Yamaha extension

(cherry picked from commit 546507fa97dc1f863b8341ec506e5bb4f6418401)
docs: Add Mopidy-InternetArchive extension

(cherry picked from commit cce6d43fcff5a316997229cf9b1eeb9286061859)
docs: Add link to coveralls.io

(cherry picked from commit be0f1ee70433ef55dda082a7c5bf56ac6b52ff44)
docs: Add Mopidy-TuneIn

(cherry picked from commit 590ce19148ad4ff4e17c1a57d8443f5a6895af17)
Add: YouTube extension
(cherry picked from commit 9b1ec31fd1aa6ddfabbbd8e89773ee0e7063d0f7)

Conflicts:
	docs/ext/external.rst
docs: Add Mopidy-Podcast-{gpodder.net,iTunes}

(cherry picked from commit 95a051abf8ff82b9b3f0484e2d343a6fc91fdfaa)
docs: Should install gstreamer0.10-alsa before using alsasink

(cherry picked from commit 9db9def367d02aef9d075721b5ce829649e61325)
docs: Make 'mopidy config' more prominent

(cherry picked from commit afbd9895bfae15e2f33b3bc1ffd6b5ea6ea3f542)