Tolerate large GTFS geographic extents

[abyrd]

This is an initial response to #779. Certain exceptions are translated to GtfsErrors to prevent them from making the feed unusable.

[trevorgerhardt]

checkWgsEnvelopeSize is also used for OSM extents. Should we continue to throw an error for OSM?

[abyrd]

checkWgsEnvelopeSize is also used for OSM extents. Should we continue to throw an error for OSM?

Yes, the strict extents checking was originally intended for OSM data since that automatically determines the default linking grid. For example, upload OSM containing islands on either side of 180 degrees longitude, and it thinks you want a grid spanning the whole Earth.

The same checks were then reused for GTFS, where the problem isn't as important because GTFS stops outside the OSM area are just not linked to the road. They cause only a marginal performance hit and it can be more trouble than it's worth to manually modify the GTFS.