Per-cell pathgrid data and calculation moved off PathFinder.  Now the edge cost calculations and strongly connected component searches are done only once per cell.  Per-actor data and methods still remain with PathFinder.

This version still has debugging statements and needs cleaning up.
Cleanup debug statements.
Make Travis happy.
Move PathgridGraph into separate files.
Remove logging.
Remove redundant parameter from aStarSearch.  Also update some comments.
One more comment fix.
Fix visual glitch happening when closing inventory while sneaking

(bug #1255)
Merge remote-tracking branch 'cc9cii/PathFinder-split'
minor cleanup