Apply Java stop consolidation files (multi-feed phase D) #1977

Java OneBusAway can merge duplicate stops across feeds with a stop consolidation file. Each line names a canonical stop and the stops it absorbs. Maglev does not read these files. In multi-agency regions, the same physical stop then shows as several stops.

The spec is the wiki page Multi-Agency-Static-Feeds-Stop-Consolidation, phase D. The work:

• Parse consolidation files exactly as Java does, and report problems in them.
• Work out what Java does with each absorbed stop.
• Remove consolidated stops during import, and apply the file on static import (stop-consolidation-url).
• Remove trips that consolidation leaves with fewer than two stop times.
• Resolve absorbed stop IDs on the stop endpoint, and translate them in realtime feeds.

The import PRs stay draft until multi-feed phases B and C land.

PRs: #1771, #1772, #1774, #1775, #1776, #1773, #1777, #1778, #1779, #1808.