Reverts [24530] & [24531] (preprocessing related) , add $(DEFS) (-DHAVE_CONFIG_H) to moc command line

Qt4 - Basic implementation of the extensions. Seem to work :D Just .avi now, because we have no good list of extensions in the source code... :D
Ref #763

Qt4 - Fix Compilation on CYGWin. This is a quick fix but not a solution. Again, MOC isn't given HAVE_CONFIG_H so it can't understand ENABLE_VLM or ENABLE_UPDATE. MOCFLAGs would fix that ?

Small fix for Windows compilation... gruiking because MOC doesn't understand #ifdef WIN32... Necessary to add a MOCFLAGS in configure.ac ?

Missing some cases that I could not test.
Also ffmpeg/chroma.c is locked, so I can but leave it broken.
Fix is for the remaining modules is obvious and the issue is easy to detect.

Qt4 - Put the dialog you are not likely to use during playback as QDialogs, meaning centered on MainInterface.
VLM, Preferences, Errors, Podcast_Conf, GotoTime, Help.

- Click on a point on the timeline goes to that point directly
- Draging the timeline makes the position follow your draging
- Hovering a point on the timeline gives you the time of the position under your cursor.

This make break your neck, and kill your favourite ant, but I think this is not that wrong.

- Don't free/delete stuff that belongs to LibVLC - closes #1397 for real.

And this has nothing to do with [24331] or [24406].

vlc_threads.h: now that vlc_object_t is optional for mutexes, make sure that we deal with it properly

Print messages directly to standard error if we don't have an object much like when malloc fails, though this time with UTF-8 support.