Remove a noop method from ChangeListenerSet. The class is final so it is not overridden by users
Fix the javadoc of Strings#getLevenshteinDistance()
Non functional:

- Java 7 diamonds
- inline member field as a local
WICKET-5778 Pass the IModifiable to the IChangeListener in ModificationWatcher

Introduce temporary interface IChangeListener2 that can be used when one needs the changed object as a parameter