!ov should warn the user when querying a town that has no train station

[Foxite]

It should find the nearest train station instead, and also warn that it cannot look up bus routes.

To do this we might need to add all towns into the list of stations, and a flag indicating if the town has a station. We also need to add the coordinate location for each item, existing and new. All of this was already present in the stations.xml file as downloaded from the NS dev page, which was stripped down when we started using it. We can download it again without stripping it down.

When the station search returns a location with no station, it should search the list again, looking for the nearest train station to the requested location. This could take a few seconds per request, so we should add a rate-limit to this feature.