New query-operators available

Two additional query-operators have been added to the rule-concept of EMFTrace.

ModelUndirectedRelatedTo - works just as the existing ModelRelatedTo-operator except for ignoring the directions of relations, which is especially useful for simplifying rules searching for equivalences.

ModelIndirectlyRelatedTo - searches for indirect relations between two models of a certain type. For example, you could use this operator to query the inheritance hierarchy of classes or call-relations between methods.