Made demux2_IsPathExtension case insensitive.
Used demux2_IsPathExtension/p_demux->b_force when appropriate
Fixed a regression in flac demuxer (segfault when reading meta data)
Added a VLC_UNUSED(x) macro to avoid seeing ugly (void)x around the code.
Improved a bit a few vlc_common.h macro (do {} while(0))

Good news is, no plugins used it anyway.
Bad news is, some parts of libvlc still use which is wrong (i_refcount is protected by the "structure lock", meaning only misc/objects.c functions can use it safely).

MacOSX/Framework: Use --opengl-provider=minimal_macosx. (Original patch by Enrique Osuna <enrique.osuna a gmail d com>).

modules/gui/minimal_macosx: Fix shortname and add shortcut, after funman answer to Enrique Osuna patch.

modules/video_output/opengl.c: Allow opengl provider override at runtime.(Original patch by Enrique Osuna <enrique.osuna a gmail d com>).

Reverse previous workaround for pthreads lib having GC2 suffix - that
is actually normal; patch should instead go into x264 to make it ignore
the presence of a local pthread lib under cygwin when doing configure tests.

Contribs: take libebml and libmatroska from released versions... Way easier to not compile it everytime.

Ignore directories in --sub-autodetect-path that match the directory
of the current file (But it does not works with symbolic links).

Fixed an overflow when more than MAX_SUBTITLE_FILES are detected.
Fixed a bunch of memory leaks.
Fixed removing sub/idx pair. (sizeof() != strlen on char*)
Clean up/Simplify (asprintf/calloc are usefull)
Cosmetics

selected one with --sub-file

 - as a standalone file
 - as a kind of subtitle (even if it is a video track).
CD-G disk are not supported.

Please, report any file incorrectly decoded. (I have 0 sample with
circular scrolling)

In subtitle_Detect, do not add as a subtitle the file for which we
are doing the detection.
 (subtitle_Detect("file.sub") returned "file.sub")

Re-enables media library.
Fixes #1047 (nth attempt).