deletion of hidden_source, and hidden_sink metabolites in hide-method
added new options for sorting order
changed detection of external metabolites (now we mark as external all metabolites that are marked as a dead-end metabolite by cbmpy, ánd the metabolites in the external_compartment)
added division by gcd when adding plus and minus rays (to keep numbers from getting unreasonably large)
made normalize_columns, and print_ecms and storing the ecms work even in case of unreasonably large numbers
Most important changes are: