Correct use of an anonymous ontology as a working copy for the debugger

For the debugger, we create an (anonymous) ontology as a working copy of the source ontology.

• now (0.1.0.BETA) we are using a real URL (http://git-ainf.aau.at) as the server-part of the working copy ontology's IRI. This however is bad practice since it seems that Protege checks the URL and contacts that server each time (especially a problem when the server is down because of maintenance reasons: Protege is unresponsive because network timeout for some seconds). Solution: We should create an anonymous ontology instead. See #40 (closed) Fixed in f68e0803
• when switching the source ontology, or each time we start a new debugging session, we have to reset() the working copy and reuse it later. Currently a new working copy is created while the previous ontology is still in memory and can be seen in File->Loaded ontology sources...
• when closing an ontology, we have to destroy() the working copy so it cannot be seen anymore in File->Loaded ontology sources...