Cell: Turn off Cophir bias reduction for now
Cell: Add unique id for each cell
Cell,Ranker: Add unique number
KdTree: Try to catch reason for holes in set of subdividing cells
Kd/Hier: More debugging info to catch holes appearing in subdivided cells
KdTree/VW: More debugging info for subdividing-cell hole
GridLocate/GridFeatureVector: Fix bugs in handling cell->label lookup; should fix holes-in-subdividing-cells problem; will invalidate saved submodels