The clip QMap has been thread safed for the occasion (and to resolve a
few bugs)
Though, it seems to miss some events sometime (without crashing,
changing position is enough to restore the render preview)

Removed some debug texts

There's still some problems on the workflow rendering if we specify a
length.

Now media isn't cloned from on vlcmedia to another, since they share
options. A new one is creater from scratch.

Snapshot is working, it just misses the workflow integration.

Extension are now stored in a specific place. FileType is now really
used in the GUI, and not hardcoded.

We now have a clean shutdown process, or at least it doesn't crash :o)