GIS Represent Tweaks

Problematic for location selector: rows which haven't been written yet (e.g. inline rows) don't have an id, yet they provide Lx data that need to be translated. I'd suggest to make this a lazy method which looks up the l10n if not present in self.l10n yet.

For this special case, represent_row can not rely in lookup_rows having been called ;) (specific to this represent, not generally for all represents).