Add information about the location of the first changeset

[LorenzoStucchi]

Mappers more confidence of mappers to welcome users that are closer to their area of mapping, so could be helpful to insert an approximate location of the area of interest where the changeset has been done.

The location could be something at the level of osm admin_level 4 or 6 or similar for EU countries NUTS1 or NUTS2.

[jbelien]

That's indeed a good idea!

I'll need to check if OSMCha provides such information.
If not, we could reverse geocode the centroid of the changeset (won't be perfect if the changeset is quite large but I don't see another way to do this).

[alesarrett]

As a possible additional improvement connected to this, it would be great if zooming in the map allows to filter the list of changesets/contributors selecting only the ones inside the visible area.

[jbelien]

@alesarrett I've split your request to a new issue: #134