Committing baseline performance data.
Preparatory refactoring -- moving grid null value into variable -- that hurt performance :(
Grid.emptyCell is an integer (255) instead of null
Remove temp variable in new Grid()
Added results of 'Comment out lines that increment perfStats counters'
Use local variables instead of arrays to store per-row and per-column counts for 0s and 1s
Don't clone grids on the recursive step, use "dancing links" style backtracking instead
Added new stat contradictionSearchReachedIdenticalRowColComparison