Removing out-of-service stops

In addition to adding/modifying existing stops, we can also add the ability to act on stops that are no longer in service (stops that exist on OSM but not in the GTFS feed). This, however, opens a few cans of worms. ## Physical Status When a stop goes out of service in GTFS, it does not necessarily mean the physical sign post, platform, etc is removed. Since OpenStreetMap data is meant to represent the state of the physical world, we do not want to actually remove the node in these cases. Instead, it's probably best to apply a [lifecycle prefix](https://wiki.openstreetmap.org/wiki/Lifecycle_prefix) such as `disused:*` to the `highway` and `public_transport` tags. This way the node still exists for human mappers to verify, and we don't lose the history if the stop ever comes back into service. ## Matching We don't want to erroneously modify stops that are actually in service, nor do we want to modify stops outside the jurisdiction of King County Metro (or whatever the designated transit agency is). This means we should be pretty strict in how we match out-of-service stops. They should meet the following criteria: - Node was not matched to any stop from GTFS data - `operator` tag EXACTLY matches the transit agency - `ref` or `gtfs:stop_id` does not appear in the GTFS stop data No further matching will be done. For example, a bare `highway=bus_stop + public_transport=platform` node will not be affected even though it does not match any of the stops in the GTFS data.