Quiescent Search

This release adds quiescent search. This means that at the end of every search it performs an additional search for each leaf node to evaluate all possible capture moves (up to some max depth or until no captures are possible).

This version plays significantly better as most of the blunders in previous versions seemed to be caused by halucinations at the end of the search due to not evaluating captures. (estimated elo increase of 250 to 300 points).