Qt: capture panel: fix segfault on null value.
Qt: capture panel: Disable advanced options instead of being silent on
late failure
Qt: correctly clear the info panel cover Art
configure: reject libavcodec >= 55

That future version is expected to remove a number of already
deprecated interfaces, such as CODEC_ID_* or the Snow codec.
VLC still uses these interfaces as of today.
Qt: unbreak the update of metadata
win32 opendir: remove broken and obsolete special mode
Make sure we use the correct luac version when using contribs
Avcodec, restore the threads count to auto

Mpeg-4, H.264, VP8 and other deadlocks with -mt have been fixed
and fuzzed by Janne, notably, since a few weeks/months.
Qt: PLSelector: add more sd icons