Tighten owned-neighborhood check

[cburstedde]

Description

The branch test-neighborhood-owned contains work in progress to improve testing the 3x3 quadrant neighborhood. We're on the way removing unneeded information when edge and/or corner connections are not requested. This would need to be finalized, the checks reduced to the minimal set of cases, and tested.

Proposed solution

Talk to me about where to begin and how to proceed with this branch.

[cburstedde]

The tip of my code to make neighborhood checks conection-type-specific is ae4db19720f01d111aa0b229d936724836003c9b.

This may need double-checking and further integration.

[cburstedde]

In view of the principle formulated in #112, it remains to check whether this branch is an actual improvement or a red herring.