* [RDF_TERM,NEW] Added rdf_typed_literal/3. Actually, the RDF term module should be reworked some day...
* [RDFS_READ] Complete rewrite of the entire module. The ambition is to significantly improve upon the RDFS predicates in swipl semweb:
** Allow reasoning within a given graph (optional).
** Allow reasoning within different regimes: RDF, RDFS, RDFD (todo), EXT (todo).
** Circumvent all the quirks in the way in which swipl semweb predicates currently work (which are incomplete, inconsistent, and unsound).