Center position of subpictures which looks better.

Conflicts:
	modules/codec/avcodec/Modules.am
	src/video_output/vout_subpictures.c

Close #4798

 * Remove legacy methods
 * Implement the GoTo method

Thanks to j-b and ivoire

really route messages to tracklist interface
fix DBUS_MPRIS_TRACKLIST_INTERFACE definition
fix CanQuit/CanRaise/HasTracklist input types

fix AddTrack function
The function has changed in mpris 2.1, but the additional parameter isn't being used by VLC (yet)

loop/repeat controls are gone, we now need a tri-state button
track change signal doesn't exist anymore in mpris 2.1 and i can't find how
we can be notified of track changes

thanks to mirsal

- exchange U and V plane to get the right colors again
- fixed some compiler warnings about signed - unsigned compare
- and some missing case entries

It also removes useless thread wake up.

Fix #4797

Signed-off-by: Felix Paul Kühne <fkuehne@videolan.org>

Warning: If credentials are required, we are going to have to assume
that KDE passes them in the URL. I have not tested if this was the case
or not. This is potentially nasty for those protocols whereby VLC does
not currently implement any login dialog. But ultimately, I would
consider this a KDE bug (if applicable).

It merely changes the mapping of track IDs. This can be used along
with --audio-track-id which is already marked safe.

This should fix Debian #466323.

I have just modified it to remove the use of vlc_thread_create(). There is
a lot of improvement that can be done to the way the thread are handled.

I have not tested it for regressions.