O: Use phrase_from_file/2 for MIME parsing, otherwise Prolog goes out of stck on giant code lists.
ADDED: ensure_format/3 now throws an exception is the non-RDF MIME type is found. This allows AP to catch this.
CHANGE: rewrote rdf_load_into_one_graph/2, not sure whether this is useful.
DEB: improved AP message.
FIX: would not work on files with no extension (and thus no type).
ADDED: put FINISHED file creation under an option.
small