* [LIST_EXT,NEW] Added pairs_to_members/2, something that is often used when exproting to GIF (first collect the edges, then extract the vertices).
* [RDF_READ,NEW] Added rdf2/4 which allows for uninstantiated graph parameter.
* [RDFS_READ,EXT] Extended rdfs_is_individual and rdfs_is_subclass with a graph parameter as in rdf2/4.
* [RDF_EXPORT,EXT] Added edge term and vertex term creators to publication predicates list.
* [RDF_EXPORT,SC] Simplified code using new LIST_EXT predicate.