1. Cleanup of RDF literal handling.
2. Extensions to VoID statistics.

* [RDF_BUILD,SC] Replaced most predicates to other locations (RDF_LIT_READ,RDF_LIT_BUILD,RDF_DATATYPE).
* [RDF_DATATYPE,SC] New module for supporting typed literal reading/writing. Use of IRIs for datatypes (no longer names).
* [RDF_DEB,SC] Removed this module; was never used.
* [RDF_LIT,SC] Relocated some predicates to RDF_LIT_READ.
* [RDF_LIT_BUILD,SC] New module, predicates were taken from other modules.
* [RDF_LIT_READ,SC] New module, predicates were taken from other modules.
* [VOID_STAT,EXT] Added support for asserting statistics of all datasets described by a loaded dataset description.
* [VOID_STAT,NEW] Added assertion of void:entities.
* [XSD,SC] Use of IRIs for datatypes (no longer names).