Destroys the current view. Should be used when the BeagleView won't be used anymore. Avoids
memory leaks and calls to objects that don't exist any longer.
Subscribes listener to every action triggered by the view or its children.
This method returns a function that, when called, undoes the subscription (removes the listener).
Subscribes listener to every change to the beagle tree. This method returns a function that,
when called, undoes the subscription (removes the listener).