Check for stop_headsign in TransitIndex

[demory]

Current, certain TransitIndex methods that return trip-based results (e.g. stopTimesForStop) only provide the headsign if trip_headsign is defined in trips.txt, ignoring stop_headsign as defined in stop_times.txt (which OTP does process -- see #438). The TransitIndex methods should also check for stop_headsign if trip_headsign is not defined.

[abyrd]

It appears that this was partially addressed in 5ef4a3e on the 0.10.x branch, but changes didn't make it into master.

[abyrd]

I now see that the transit index API returns TripTimeShort objects to represent the stoptimes within a trip. Each TripTimeShort (one for each stop on the trip) has a headsign field. This headsign field is set using the getHeadsign method on the trip times, which checks for a per-stop headsign and falls back to the headsign for the entire trip if there is no array of per-stop headsigns. So it looks like this issue is solved.

What threw me off is that all the old index API model classes are still in the OTP repo, including StopTime but they are not used anywhere. I'll clean them out.