Use 'reversegeo' alt geometries

[missinglink]

Some records have 'alternative geometries' for reverse geocoding which are significantly smaller in size and complexity.
Supporting these polygons may help to reduce RAM usage:

eg:
https://github.com/whosonfirst-data/whosonfirst-data-admin-nz/blob/master/data/856/333/45/85633345-alt-whosonfirst-reversegeo.geojson

[stepps00]

For what it's worth, the "default" record should have a pointer to the reversegeo filename in it's properties. For this record of New Zealand (85633345), the record has the following property:

  reversegeo:geometry":"85633345-alt-whosonfirst-reversegeo.geojson"

Property info: https://github.com/whosonfirst/whosonfirst-properties/tree/master/properties/reversegeo

[missinglink]

@stepps00 how common/uncommon a thing is the reversegeo polygon?
I'm guessing it's mostly relevant for country and possibly region records and even then it's not super common?