* Added support of whell for slider with GTK2

* configure.ac.in, modules/codec/ffmpeg/ffmpeg.c: fixed my last breakage in the ffmpeg detection code.

* configure.ac.in : disabled compiling the old mpeg_video plug-in, so :
DO NOT FORGET TO INSTALL LIBMPEG2 AND COMPILE WITH --enable-libmpeg2

* configure.ac.in, modules/codec/ffmpeg/*, modules/encoder/ffmpeg/*, modules/stream_out/transcode.c: fixed detection of the ffmpeg headers/libs when they are installed in their default location.

  But it's coooooool. http://sidekick.student.utwente.nl/videolan/transparent.jpg

  corresponding menu. On thy fly filter changes are still not possible.

* Filling GTK2Graphics and GTK2Region destructors

    redefinitions when linking twice with the same static libary.

 It's far from stable, produce file unplayable by mplayer at least,
and doesn't yet take care of video/audio synchro.
Becarefull that the header is written only when closing, and there is
no way to repair a mp4 file without its header.

* double-click is now implemented

* Added functionnality to region

* oups forgot to commit this one. still the hide/show thing.

* Timer for text control are working badly but it's the first step

and use ffmpeg postprocessing instead of vlc builtins. (It's a lot faster).

* gtk2_window.cpp: removed fading transition delay
* vlcproc.cpp: removed warning