* [RDF_DATASET,NEW] Added rdf_assert_dataset/3.
* [RDF_SERIAL,EXT] rdf_load/3 works for URLs now.
* [RDF_SERIAL,EXT] VoID files are automatically loaded.
* [RDF_SERIAL,EXT] Improved support for writing N-Triples. Almost working...
* [VOID_FILE,NEW] Added void_load(+Graph).