…nish events

Conflict files fixed up to a state where tests pass again before commit.

Conflicts:
	mopidy/audio/actor.py
	mopidy/audio/listener.py
	tests/audio/test_actor.py
	tests/audio/test_listener.py

…the corresponding URL

audio: Scanner adds images with the URL from musicbrainz album ID

raspi: Workaround for RasPi selecting jack server.

…r-gapless

audio: Preparation work for gapless playback support

This fixes an issue where I sometimes would get an error from dbus
'Unable to guess signature from an empty list'. After some digging
and checking the avahi dbus specs I found they expect the text list
to have a signature of 'aay' (an array of arrays containing bytes).
So instead of using python lists we now use a 'typed' dbus array.

It is not clear to me why this is a heisenbug, but this fix does
seem to make it go away.

Conflicts:
	docs/changelog.rst

This adds an extra mopidy.audio.gst logger and moves the GStreamer logging to
it. Additionally this adds more logging so we can likely get by with just
mopidy logs in more cases.

This also lays some basic ground work for handling multiple outputs.

notify::source and setup-source are the same, just that setup-source is a
convenience wrapper.

This rips the mixer bits and pieces that have been hiding in the audio actor to
it's own class. The software mixer now only knows about this and nothing else
from audio.

This makes it possible to see that we setup and teardown the same things. Also
fixes disconnect on a signal we no longer listen to.

mopidy.audio.actor refactoring and cleanups

… also stored.

…ck-history