Finished the implementation of the RDF table model.

* [AP_DB,AP_TABLE,CKAN_AP,CKAN_SCRAPE,SC] Missing module imports.
* [RDF_HTML_TABLE,EXT] Finished implementing the generation of HTML for the RDF table assertion model.
* [RDF_LIST,NEW] Added rdf_list_nth0/3.
* [RDF_TABLE,EXT] Finished implementing the RDF table assertion model.
* [RDF_HTML_TABLE,FIX] Variable renaming.