Integrate BART elevator dimensions into itinerary

[graue]

Request from someone with a big cargo bike, for whom some BART stations' elevators are impossible, others difficult/unpleasant based on the diagonal.

[graue]

Would have to scrape out of this PDF

Then somehow associate each with a stop_id representing the BART station (stop with location_type=1). The stop_ids are not guaranteed not to change in future versions of the GTFS, unfortunately, and their string names currently don't exactly match, e.g. PDF: "19th St./Oakland" vs GTFS: "19TH St Oakland BART"