Remove duplicate facilities introduced by infilling

[brynpickering]

What can be improved?

Infilling even when there are some facilities in a landuse area (introduced in #49) often leads to some points being added that are duplicates of existing facilities.

We can remove these by doing a spatial join to find which infill points exist in existing facility polygons. We can use average facility footprint to approximate those existing facilities that are only points.

This should possibly be configurable since using address points to infill land use areas (#46) can infill multiple facilities in the same place if they have effectively the same address (e.g. flats).

Version

v0.2.0