Change serial version id for identifiable entity and other minor issues
Fix empty protected titlecaches #5763
Adapt clone method for credits and rights to be consistent with JPA
mapping (not reusable).
Cleanup MediaRepresentationPart and PolytomousKeyNode #5756
Remove cascading to terms #5755
Add orphanRemoval to RelationshipTermBase.inverseRepresentation
Same exists for TermBase.representation so we have consistent behavior
now. Also it makes sense as inverse Representations can not stand alone.
Remove cascade from term to vocabulary #5754
Add removed factory method for identifiers #5743
Add getter/setter for preferredStableIdentifier #5606
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