VLCKit 2.2.0-pre1

This preversion of 2.2.0 of VLCKit adds numerous features, notably for MobileVLCKit.

It notably adds:
 - VLCMediaThumbnailer as a public API for all OSes,
 - Standalone compilation of the framework,
 - VLCMediaListPlayer and VLCMedia APIs
 - New samples to build the application
This tag has no release notes.