Picture resources where not released when VOUT_DISPLAY_RESET_PICTURES
was called while direct rendering was used.

This fixes problems with hiding the cursor while it is within the
"black bars". This should also improve gestures usability.

TODO:
 - use application names for input items
 - add an item for the whole desktop,
 - add items for XRandR outputs.

This cannot work the way VLC links its plugins. Too many people shot
themselves in the foot with this option.

Unparented dialogs are not supported by the window manager. This was
causing a deadlock during VLC startup (There may be other cases left).

QSystremTray class does not exist at all.

Nothing has been using this for a while (how long?). We still have
import for old VLC playlists, though I'm not sure if anybody uses it
either.

Otherwise, checking for forced demux does not make much sense.

Without this when scanning, we would force demuxer to ts but outputted m3u-playlist.

Thanks to nefrir and mfwitten on irc for their help

The fix from quality in [8d8844ad] introduced a weird artefact with dual screens, where the video didn't fill the complete screen. This fixes it.

Closes #2885

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>