This is a traft of spatial 'intersects'.

The complete workflow outlines as such (this probably reads best in GitHub):
- Split posted geometry into dim-2 (->`related_GeoJSON`) and dim-1,0 objects
  (->`skipped`),
- In case of `contains`/`intersects`, determine one point and its side-ness
  w/r/t `related_GeoJSON`,
- In case of `contains`, set `relates` to a function that returns true, only if
  all points of a given `GeoJSON` are inside `related_GeoJSON`. As soon as one
  point is found to be outside `related_GeoJSON`, the `relates` quits early and
  returns false.
- In case of `inside`, set `outside_A` to a function that returns true, if all
  points of `GeoJSON` lie outside `related_GeoJSON`; This is the same function
  as above, just with the side-ness flipped (neat).