Modified:
	- Structure of GreedyIncrementalPlacer to make the creation of a
new placer to place from the leftmost column to the rightmost, one at a
time. (Which should be faster.)
	- Made the loop in (previously) place_queens exit early, which
	  DRASTICALLY enhanced performance
	- Board class now handles amount of queens on board - looks
	  nicer in code and makes more sense imo