Design deprecation mechanism

[cpfaff]

We agreed that concepts stay forever but might end up being deprecated if the ontology is developing. @naouelkaram could you make a suggestion on how to model this?

[naouelkaram]

This can be done by adding the following property to the deprecated class:
<owl:deprecated rdf:datatype="http://www.w3.org/2001/XMLSchema#boolean">true</owl:deprecated>