ncurses: base detection of wide characters support on the presence of libncursesw, and use the same header wether it's present or not

Add mkv file extension as ffmpeg now can mux to Matroska.

Preferences for dummies ( #603 ) is now almost done in Qt4. Please test and review my commits.

Qt4 - Preferences, don't remove the widgets to re-add them! Just use hide/show... A stackedLayout would have been a better idea, but this should work.
Please report any breakage, as it might be wrong somewhere.

Qt4 - Prefs; cleaning, disabling unused code, general comments, class renaming, in order to actually use those preferences. :D

Gosh, who wrote those simple Preferences ? Seriously ?
ooooooooooooooops...

The change in configure.ac is suboptimal. It would be better to change DEFAULT_INCLUDES to use -I${top_builddir}/include rather than -I${top_builddir}. Automake wizard requested.

net/if.h depends on it on some systems (Darwin & FreeBSD at least)

Qt4 - SPrefs, device selection. Please Review, since I am far from sure that this is a good idea... 
Moreover, is it config_PutPsz( p, name, ASCII ) or  config_PutPsz( p, name, UTF-8 )  ?

* fixed Apple Remote support for Leopard. Note that the cookie for kRemoteControl_Switched wasn't updated, but since we don't use this feature in VLC, that's pretty fine.