Able to use PlayN as a part of application

Registers the application using the supplied configuration and window. 

The window is used for a game integrated as a part of application. An iOS application typically just works on one screen so that the game has to share the window created by other controllers (typically created by the story board). If no window is specified, the platform will create one taking over the whole application. 

The lifecyle management should be carefully designed and implemented when cooperating with other controllers. At least, the UIApplicationDelegate.OnActivated(UIApplication) should be called to avoid the frozen graphics.