Always display GTFS-rt alerts without a TimeRange

According to the spec:
"If missing, the alert will be shown as long as it appears in the feed.
If multiple ranges are given, the alert will be shown during all of
them."
Set agency to default value during GTFS import
Add graph configuration option to in-memory graph service
Configure "0MQ" (misnomer) updater through properties file
Merge commit '19b6e22'; commit '8cfe766' into stop_data
Accept only identical Place objects at transit/non-transit leg boundaries
Simplify and improve generateItinerary()
Store stopSequences in TripTimes

This is essentially commit 84bc91e0be5c7d57a59169f0eea43daea05c55be cherry picked by hand.
Require stop sequence numbers in PlanGeneratorTest
Add stop sequence numbers to API
Rename getStartStop() to getBeginStop()
Add test for time-based onboard departure during dwell time at a station
Allow onboard depart during dwell time at stations
Merge remote-tracking branch 'goabout/onboard_station' into mmri-rt
Pull TransitStation vertex type out of TransitStop
Merge Jaap's single transfer paths test (7f2afa0)
Allow paths that consist of a single transfer
Test difference between STATION_STOP and STOP_STATION
Allow current vertex type to influence terminalFor
Merge remote-tracking branch 'goabout/parent_station_vertices' into mmri-rt