Fix crashing, but still going in straight lines.

Do appear to be going to tiles...corners anyway, that's ok
But shortest path...isn't reall shortest.  Futz with move costs.
Shortest path never ends....

It looks for new tiles to see if they're in the open or closed list
but it's really only looking at the pointers!  change all these
lists to lists of pathpts, no need for pointers
No longer crashes.

I still don't think it's really doing shortest path though.