Finalized RDF(S) materialization. Now to be tested...

* [DB_EXT,FIX] Added missing meta_predicate/1 declaration.
* [RDF_TMS,EXT] Effectuated BNode2Literal mapping in RDF(S) materialization.
* [RDF_TMS,DEB] Added debug predicate rdf_tms_test1/1.
* [RELATIONS,FIX] Added missing meta_predicate/1 declarations.