Fix: #8447

libmpgatofixed32: return ENOMEM instead -1 and VLC_SUCCESS instead of 0, also set pf_audio_filter after everything is ready

Should Fix: #8434

If playlists containing youtube urls are exported or imported, these patches
improve the usability of the playlist.

Lua remembers the original url (i.e. the website _containing_ the content) if
no other url is passed by the lua parsers. It also puts the content title to
the meta-title entry.

XSPF export / import now uses the <info> to deal with the meta-url.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

In ACTIONID_SUBPOS_UP/DOWN, do not change subtitle position if there
is no subtitle, or if subtitle has been currently disabled.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

In ACTIONID_SUBDELAY_UP/DOWN, do not delay subtitle if there is none,
or if subtitle has been currently disabled.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

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

Close #7900

Close #7899

Candidate user patch takes a different approach.

This reverts commit c38081e5.

More control elements to come

Needs some more testing, especially on embedded platforms

(However support for IMMNotificationClient remains missing.)

There are no simple ways to find the right proxy on Android, even in
Java. A proposed "solution" is suggested in the comments, but it would
require JNI. Feel free to implement :)

Added the following shortcuts (and made them configurable):
 - Shift-H: sets a timestamp bookmark on the audio
 - Shift-J: sets a timestamp bookmark on the subtitle
 - Shift-K: corrects the delay between both bookmarks
 - Command-Shift-K: resets the delay

See http://forum.videolan.org/viewtopic.php?f=7&t=109641 for an
illustration of a possible use
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>