Add implementation classes from extended aspects and reused concerns to selection

[Matthias Schoettle]

When reusing a concern that contains implementation classes from a third-party library:

Assuming the user wants to create an association from one of his classes to one of the implementation classes to be able to use it throughout. By default, the user needs to add the JAR of that library first.

It would be very helpful, if the selector for implementation classes in addition to those loaded through the class loader would also include those that ar located in an extended aspect (at least concern public) or a reused concern aspect model (public).