I think constructors make sense for initializing things. There's an `init` function in model which parallels the constructor here... I think it's just more common practice to use a constructor. I'm actually not using the `MessageCursor` in a way that implies multiple instances (since all of the communication with the cards is done through the singleton `MessageCursor.inst`). I could be convinced though, for clarity sake and for the time being when there's only one of these guys, to export `MessageCursor.inst` instead of `MessageCursor`.