on heuristic consistency log _plus_ lifting up h to zero if previously less-than-zero
Merge branch 'v.4.6.1' into v.4.6
on refining how to compute est-cost2go vs. true-cost2go
Merge branch 'v.4.6.2' into v.4.6
Merge pull request #36 from tttor/v.4.6

V.4.6