Shapes.txt lines need to be cleaned up

[junosuarez]

Per @aplannersguide, currently these are generated from GPS tracks on the buses themselves, which run from the central bus depot all along the routes, even when the bus is not in service. The routes in shapes.txt should only be when the bus is in service.

Options to explore moving forward:

1. manual clean up in GIS
2. redraw the routes using Transitmix and then export that back to GTFS (cc @samhashemi @invisiblefunnel - is this possible to export just for the shapes.txt file?)

The shapes.txt file is currently updated with each new markup (every time the schedule data is updated, about twice a year), so these processes would have to be repeated at that time.