[RB] Removing a class should ignore reference to the class by the class itself

[Ducasse]

When we remove a class, the preconditions check for references to this class.
However it should ignore the reference to the class from the class itself.

[AlexisCnockaert]

I created dummy classes with one reference to itself and one reference from an other class.
The reference by the class itself does not appear so I can't reproduce it, only the reference from an external class is taked into account

[AlexisCnockaert]

I will create a PR anyway because the browseReferences choice was raising an error