DRAFT: Universal VLCKit.framework for macOS, iOS, tvOS

WORK IN PROGRESS (WIP) for #671

To build:

1. Open Xcode project
2. Go to the "StaticLibVLC" target
   1. Go to "Build Phases"
   2. Go to "Link Binary With Libraries
   3. Click the "+" button
   4. Click "Add Other..."
   5. Click "Add Files..."
   6. In the open dialog box, find your compiled libvlc-platforom-static.a
3. At the top of Xcode, select the "VLCKit" scheme
4. Select the respective platform (i.e., "My Mac", "Any iOS Device", etc.) to match your libvlc-platform-static.a file
5. Press CMD-B or press the Play button