Skeleton web worker for long-running analyses.
Skeleton solver worker.

It just makes a lot of noise at the moment.
First draft of working search, but only finds minimal solutions
Working search that finds all solutions, but no heuristics yet.
Remove unused `shortest` function
Clever and less-clever heuristics, though the clever one is likelier to be inadmissible.
Use object centroids to hash-index states and process much faster