* [RDF_ENT,RDFS_ENT,RDF_MAT,SC] Removed all regime/[1,2] clauses.
Work on cleaning up the codebase, focussing on set theory and prolog modes.

* [DIR_EXT,SC] Added run_in_working_directory/2, coming from META_EXT.
* [ERROR_EXT,NEW] Added mode_error/2 for predicates that do not have the required mode (det,semidet,nondet,multi).
* [HTML_LIST,SC] Renamed html_link_list//2 to html_handler_list//2, refering to http_handler/3.
* [PROLOG_CONTROL,NEW] New module for control structures in Prolog, coming from META_EXT.
* [PROLOG_MODE,NEW] New module on Prolog modes (det, nondet, multi, semidet).
* [RDF_TERM,EXT] Use mode enforcement on rdf_name/2.
* [SET_THEORY,NEW] Added wrapper superset/2.
* [SET_THEORY,SC] Big cleanup: much more concise implementation of delete_supersets/4.
* [SET_THEORY,EXT] subsets/2 did not gice subsets but binary filters. These are now used to return the actual subsets (using binary_overlay/3).
* [SORT_EXT,SC] New module, taking code from META_EXT.
* [LIST_EXT,EXT] Rewrote repeating_list/3. Throws an error on negative `Repetitions` value. Better documentation of instantiation and mode.
* [META_EXT,SC] Removed superfluous list_compound/2 method.
* [PROLOG_MODE,SC] Removed superfluous nonvar_det/1. Replaced by the more generic enforce_mode/2.