Added new module for automating the processing of RDF data.

* [AP_STAGE,NEW] Added args/1 option for adding an arbitrary number of arbitrary parameters to the custom goal.
* [FILE_EXT,NEW] Added wrapper file_directory_alternative/3.
* [RDF_AP,NEW] New module automating the often-occuring process of loading, merging, processing, and then saving and unloading a couple of RDF graphs from files.
* [RDF_SERIAL,SC] Some code was moved to RDF_AP.