1. Consolidation of XSD cleanup.
2. Make CKAN download work again.

* [AP,FIX] Determinism for RDFS label lookup.
* [AP_DB,FIX] Do not assert skipped stages as succeeded stages.
* [AP_DIR,FIX] Removed superfluous atom/codes conversion.
* [CKAN_DOWNLOAD,SC] Reuse of existing predicate for file download.
* [CODES_EXT,FIX] Added deterministic mode for atomic_codes/[2,3].
* [DCG_CARDINAL,FIX] Added deterministic mode for decimal_digit//2. What about all the others?
* [DCG_GENERICS,FIX] Loop in dch_phrase/2.
* [HTML,EXT] Added HTML dialect option to download_html/3.
* [META_EXT,NEW] Added temporarily_set_flag/3.
* [RDF_DATATYPE,SC] Renamed rdf_datatype/3 top rdf_lexical_map/3.
* [RDF_DATATYPE,SC] Cleanup of RDF datatype code based on the big cleanup that was performed in the XSD codebase.
* [XSD,SC] Simplified calling lexical maps.
* [XSD_DECIMAL,SC] Module import cleanup.
* [XSD_NUMBER_GENERIC,FIX] Added determinism to the canonical map.
* [XSD_STRING,FIX] Added determinism to the canonical and lexical maps.