Version 4 roundtrip test case fixing & breaking.

This change set fixes a number of failures due to test harness issues, and stops ignoring all but json-ld round trip tests.

This change set leaves a number of tests actively failing, due to errors in the code (hence there not being ignored). 

1. PrefixOntologyFormatTestCase is failing for N-Triples and N-Quads.  This is unsurprising, as these formats do not in fact support prefixes.  However for some reason,  AbstractRDFDocumentFormat extends PrefixDocumentFormatImpl ... 

2. Test cases for Annotated Nary  Equivalent Classes, DataProperties, and Object Properties fail for NQuads, NTriples, and NTrig.
EquivalentClasses are left as binary equivalences; all annotations are lost. 
EquivalentDataProperties and EquivalentObjectProperties are also left as binary axioms;  annotations are attached to one of these axioms.

3. DataUnionOfTestCase2 fails for NQuads, NTriples, and NTrig ; the problem appears to be due to  anonymous data types being reused.  I am not sure if this is an error in the renderer or the parser;  the rendering of the NTrig is not reassuring.  I should try and make a gist.