[MediaFoundation] Fix invalid implem of MediaEventGenerator.GetEvent isBlocking
[MediaFoundation] Add MediaSessionCallback to provide a default callback to handle MediaSession events
[MediaFoundation] Clear AsyncResult.NativePointer once used by the callback in order to avoir false-positive log in ObjectTracker
[MediaFoundation] Fix compilation on Windows App and Phone 8
[Toolkit.Graphics] Fixed exception at changing fullscreen state with adapters which don't have any output (for example, like WARP)
[Toolkit.Graphics] Fixed github issue #95