Don't calculate or store small (1000 bp) block size as this isn't used by the web code or anywhere else.

added parent to the unmapped_object table to allow adding what the parent was for depenednet xrefs etc

Make target connection details default to source if not specified.

clean up of unmapped objects no longer an option but enforced as external_db_id also added to the delete line to ensure safety

Allow specification of up to 3 separate databases: one to read transcripts from, one to read oligo features from, oe to write xrefs to.

By default, check if there are existing xrefs (for all or user-specified arrays) and exit if there are. Only delete if -delete is explicitly specified.