Miscellaneous editor fixes for SunRail

[landonreed]

From @alexander-lew-ibigroup:

Bugs:

• [ ] When typing in the Offset field on the Timetable editor, it would switch to random numbers. Not sure exactly why.
• [ ] When editing the name of a trip pattern, it would occasionally switch back to the old name.
• [ ] When changing trip_ids, if you used the trip_id before, it would throw an error. While duplicate trip_ids would make the GTFS invalid, it made it more difficult when changing multiple trip names.

Enhancements that would have been useful:

• [ ] A lot of optional GTFS fields are in the GTFS export with null values instead of not having the field at all. This caused some issues when I imported the GTFS into the SunRail prediction system.
• [ ] Offsets by seconds: it would have been useful to have this since we have 30 second dwells and it's the departure time that is on the :00 instead of the arrival time.
• [ ] Trip short name: can't customize the trip short name, which we use to identify our train numbers (especially if trip_ids are changing). I ended up adding these manually in excel.
• [ ] Pickup_type and drop_off type in stop_times also couldn't be customized, and had to add these with excel as well.