Updated the data model approach in OSSTIP a bit:-
 * All routes now have an ID.
 * Instead of segs storing a list of route names they're part of, now
   they store a list of route IDs they are part of.

This means there is a little bit more mapping between route ID -> name to be
done in some places, but makes the code more precise and error-resistant to
the problem e.g. in buses of multiple routes having the same short name.