Cleanup; change in init_open_and_closed.
Cleanup; change in init_open_and_closed.

I believe that the initial nodes inserted don't actually need to have
non-zero heuristic values set---they will be expanded first, when they
are the only nodes in their respective queues, and will then no longer
be in the open lists.

I am still getting suboptimal results.  Maddening!

bradlarsen/switchback,bradlarsen/switchback