This adapts to two changes in place handling by Nominatim:
* Place links that are computed by Nominatim are now found in
extratags['linked_places']. Keep the check for extratags['place']
as this may contain an explicitly mapped place label.
* Use address rank for guessing the admin level. This gets normalised
by Nominatim with respect to country-specific use of admin_level.
Also adds additional labels for admin levels, so that we now have
complete coverage for all levels that are in use in OSM.
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