Updates for OWL-identity sets.

* [DBPEDIA,SC] Simplified the implementation for assering (identity) resources using the new OWL identity predicate (see module OWL_READ).
* [META_EXT,NEW] Added update_datastructure that allows an arbitrary goal to update a given datastructure continuously for a given list of arguments. (Used for building OWL identity sets.)
* [OWL_READ,NEW] Added owl_identity_set/2 for finding the set of OWL-identical resources.
* [PRINT_EXT,SC] Renamed meta option `transformation` (too generic) to `ordering` (i.e., the transformation applied to the ordering of a collection of objects).
Merge branch 'master' of https://github.com/wouterbeek/PrologGenericsCollection