Updates:
- New class added: StartFrame.
- Application now starts up by popping up a window (StartFrame) that asks the user to choose a map (Krak or OSM).
- StartFrame runs on one thread, while the initialization of the other classes (MapPanel, MapView, Controller) is done in a worker thread.
- User can only choose map when the (Krak) map has been loaded, meaning when the worker thread is done.
- The windows now starts up in the middle on the screen.
- Closing the map window no longer closes the application. The user has to close the StartFrame.