Adds bus access to alleyway consistent with GTFS and other OSM relations for bus routes

Reverts earlier edit at WMATA Southern Avenue Station, converts busway (it's not) to a service road with bus=designated, address some directionality, level, and access issues.

Using proprietary bus GPS trace and public GTFS, confirmed buses turn left in to bus service road here. Added new segment to reflect this turn. Some turn restrictions may be a bit excessive, but should improve routing with the new segment.

Additional fixes to WMATA Southern Avenue Station, including changing building to overpass pedestrian bridge, coding small bridge over metro tracks, and clarifying layers.

Updates to bus access. Based on GTFS data, confirmed with mapillary

Updates to bus access. Based on GTFS data, confirmed with mapillary

Updates to turn restrictions to add exceptions for buses, fix an erroneous turn restriction at I & 17th St NW in DC. Sourced from local knowledge, confirmed with mapillary

Added turn exception for bus and taxi per local knowledge and confirmed in Mapillary imagery.