Add additional bin-packing constraints

[jonadsimon]

Can efficiently add bin-packing constraints if we know (1) for each word pair, do they share a letter? (can pre-compute) (2) for each horizontal/vertical, how many words intersect it (similar to "does this word intersect this square" logic)

Understand how rotations are/were handled, to see if they can be extended to diagonals

[jonadsimon]

Re-watched the relevant Coursera lectures, and none of the suggested constraints would help. Once the myriad of allowed-overlaps are added in, the constraints would be so loose as to be useless.