Add risky efficiency

[nineteendo]

Deployed here (with the changes from all 4 PRs): https://nineteendo.github.io/JSMinesweeper

This swaps the 2 lines in the efficiency helper.

It's looks like it's able to abuse the start tile (if this is desirable, you could use the efficiency helper for making guesses):

This doesn't seem like the best move though:

seed 1936646677345255 (efficiency 140.58%):

[nineteendo]

Hmm, it currently uses tiles as actions, that isn't right.
Edit: fixed.