Feature request: "last run" field in departures API

[Nate-Wessel]

Of course, this could cause problems if this is used for other systems that operate around the clock.

Basically, we would need to select the trip with the MAX(arrival_time::interval) GROUP BY route_id, service_id (potentially, you could also throw headsign into the group by clause which would cause some help and confusion for routes like the 43 with many parts)