ref: cd67072556c6b5934005b1777a465aca1e9df545
parent: 12fabc4add608622da87096bb3bed586efee10d9
author: Jonas Kölker <jonaskoelker@yahoo.com>
date: Thu Oct 8 08:55:52 EDT 2015
Add standalone Fifteen solver, based on the hint feature. Recall that the hint feature is really an incremental solver. Apply it repeatedly until the board is solved. Grade puzzles as solvable or unsolvable by checking their parity.