Add ENABLE_NLS define, and make po files optional
Update source files to latest modifications
Add missing function checks
Define QT4LOCALEDIR
Require ncurses (I will submit a patch to cmake to check for ncursesw)

Note that an upper limit should be set anyway

This reverts commit e31c7798.

Damned, this is a hack to display psz_cat in the playlist.

So that vlc --{list,help,module} don't get us a non-null exit code

(cherry picked from commit a2d82490555eb3271a77b4958bc8528091951901)

Conflicts:

	modules/control/rc.c

/!\ In pure C, `()` means `(...)`, not `(void)`

This reverts commit f3b97438.

It creates a circular reference holding. (playlist is the parent of the preparser and hold a reference to the preparser during all the preparser life's span).

(Not-So-Dumb-References-Checker IDentifier one)

I saw you, evil preparser thread...