1. ADDED: Rewrote RDF datatype support entirely.
     - Comparator and equivalence on value space.
     - Support for rdf:HTML and rdf:XMLLiteral.
     - Consistent value -> lexical form mapping for assert/retractall predicates.
     - Consistent lexical form -> value mapping for read predicates.
2. ADDED: Rewrote RDF list support entirely:
     - Consistency with LIST_EXT.
     - Optional graph argument.
     - Use of closures.
3. CLEANUP: Removed superfluous predicates. Reordering of predicates over modules.