Hasher, equality tester, and Trove custom hash strategery for comparing OWL Objects matching xsd:string to PlainLiteral with no language, and rdf:langString to PlainLiteral with lang tag.

New code used in round trip test.

JsonLD brought under test.

JSONLD marked as non-Prefix aware.
Remove overrides hiding possibly failing tests  - if a test  isn't passing, it should be seen to fail, or should be explicitly ignored.

 Ignorance isn't bliss.

 [oddly, some of the tests actually pass, and a few  RDF/XML renderings throw errors]
Use correctly formatted urns (maybe we ought to check for this).
Use correctly formatted urns (maybe we ought to check for this).