mvmOS 0.27.0-beta: Manage your licence key in Settings

Settings has a new Subscription tab. Enter your premium licence key there, see whether it is currently active, and remove it again. Your installation revalidates the key with mvmos.org on a schedule rather than only at the moment you type it in, so an expired or moved licence is noticed on its own. Settings also moves out of the app list into its own Start Menu entry, and a premium badge next to the signed-in user opens the Subscription tab directly.