Rewording of some categories of Preferences, avoid "General" as a title and using "VLC", every other two lines...

Grrr a library that does exit on its own !

Noticed by courmish.

(X11 has a similar bug, not to how to fix it)

It fixes an assert in vout code when a stream was stopped while paused.

It was created as an integer and set as a boolean...

N.B.: libvlc snapshots remain seriously broken.
Vout is not locked when shooting. Variables are not safely set.
Vout thread does not access request field safely.
Multiple requests are not safe either. I probably missed some other
issues.

C++ is always so much fun ;)

It still does not work because of [2413].