3.0: backport VLCMediaPlayer's initWithLibrary

There is already initWithLibVLCInstance but it's using an existing player instance, and initWithDrawable:options: which initialize a new libvlc instance.

Initializing from an existing VLCLibrary allows sharing the VLCLibrary among multiple VLCMediaPLayer and setting up logger callback on an instance basis before allocating the VLCMediaPlayer.

(cherry picked from commit 77141ee2) Signed-off-by: Felix Paul Kühne felix@feepk.net