Retire Event Ontology

[hauschke]

What is the motivation for your change request?
Currently one class and no properties are being used from the Event Ontology http://purl.org/NET/c4dm/event.owl# in the VIVO Ontology. As already argumented by Mike in the "early thoughts on a VIVO subsumption hierarchy", event can be a VIVO term. This would make a) the ontology more consistent, as this is clearly in scope, and b) would make it easier to maintain external dependencies in future.

Describe the solution you'd like
Create vivo:Event, deprecate event:event. The new VIVO class should completely replace the current loaned term from the event ontology.

Describe alternatives you've considered
We could keep it.