[LMP] Properly catch resolve errors.
[LMP] Code style fix.
[LMP] Fix saving no sorting.
[LMP] Better error handling for #1483.

Know gstreamer's File Not Found error.
[LMP] Avoid dbg output on stream status change.
[LMP] Bus drain kludge for #1483.

GStreamer sends some error messages multiple times for some reason, so we
should drain all of them after we get first one so that it wouldn't
interfere with the state of the pipeline after we handle the first error
message.
[LMP] Playing state change should notify about the song.

For #1483, also probably fixes #1480.
[LMP] Skip to next track on SourceNotFound error.

This finally fixes #1483.