contribs: added Google's libvpx patch for ffmpeg with a couple of compilation fixes for Mac OS X and added another patch for libvpx

Please note that updating pre1 to pre3 won't work because of this missing key *cough*

Mac OS X: added various missing file extensions to the supported-by-this-application-list (xa, m3u8, b4s, vlc, xm, amr, aob, dts, cdg, idx, oma, voc, vqf, mpeg1, mpeg2, mpeg4, mts, mid, mlp, webm, rar, rec, rmi, s3m, vro, tod, utf)

This should fix usage on windows.

This removes a dangerous vlc_object_find(PARENT) and potentially
invalids var_DelCallback().
It also avoids useless callback destructions and so fixes some dvd menus.

It will simplify improvements of vout_Request.

Don't use the iphone-trick, but instead parse the playlist-file and add
all the video-types on one run. Seems that when adding nodes on lua sd plugin,
theres some flickering.

It seems that decoders not using AVContext::get_buffer() do not
initialize AVFrame::reordered_opaque.

It basically works but they are some issues to be fixed.

This close #3646

Signed-off-by: Christophe Mutricy <xtophe@videolan.org>

Signed-off-by: Christophe Mutricy <xtophe@videolan.org>

This prevented the play time from being updated correctly in the
interface when seeking backwards

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

based on feedback from fenrir, looks nicer too.

Thisways find_stream_info() doesn't get stuck with some http-streams (like
http://bglive-a.bitgravity.com/twit/live/high ) when trying to seek. Fix #3080

The library buildsystem is a MESS, and I am polite...
The patch is a bad workaround for the wait of a better solution.
Is google really that low a standard? Maybe they should recrute other people...

Only tested on Win32 so far

it should read 'TL/TL and BR/BL' instead of 'TL/TL and TL/BL'

These features include

for vlc11
 - new variables : vlc.canRecord and vlc.isRecording
 - new functions : vlc.toggleRecord() and vlc.nextFrame()
 - a new 'loop' parameter for animated bitmaps
 - a special id="fullscreenController" for Window, intended to be
   used as a skinnable fullscreen controller

for vlc12
 - a new 'art' parameter for image control
 - a new 'scale2' value for resize parameter of image control