Fixed the order of these.
Added code to handle window close in a better way. This got a bit awkward since we have to run some code reasonably early; earlier than we are able with e.g. Dispatcher.ShutdownStarted and similar… We probably have to have some Unloaded() code nonetheless, to not leak so incredibly much memory. ;-) But that have to be fixed a bit later. Closes: #140.
Let's not pretend to play the IDisposable game. It's not really supported for WPF controls anyway.