Close #7133

Close #6578

The code is far from being great, but it matches the Qt intf now.

Fix #1859 #6983

Depending on the system, this can be called ducking, focus, policy...
But it basically boils down to pausing playback automatically when a
higher priority audio stream starts, typically a voice call.

Resuming playback automatically when communications are over would be
possible as well. But that seems unfriendly to me, so I skipped it.

This was not tested due to lack of hardware.

This reverts commit 12627b88.

Modified-by: Rafaël Carré <funman@videolan.org>
Signed-off-by: Rafaël Carré <funman@videolan.org>

VLC has a native parser with higher priority. So ModPlug only got to
parse the broken files that VLC rejected. ModPlug is not robust and it
crashes in that case.

(support for webm and Opus)

YUY2-specific transforms are required only when inverting dimensions.
For flips, normal single plane 32-bits pixels transforms must be used.

The broken transform functions were not used, but they were referenced
via relocations.

macosx/fspanel: allow continued clicks on the backward/forward buttons like we do in windowed mode (close #7258)