Weight adjustment menu, castling thru check bug fixed
-There's now a menu where you can tweak the weights the engine uses for material, position, and bonus scoring.
-Fixed a bug where the engine would try to castle through and into pawn checks, because the pawn didn't think it could attack the given square because the king wasn't on it yet.  Now the move to the inbetween squares and the final square are simulated so pawns will know if they can go to that square.
-Changed killer move arraylist to hold moves, not nodes, so that references to the nodes get released when the node does.
-Fixed bug where resetting the game doesn't reset the list of captured pieces, resulting in an accumulation of pieces for multiple games.
-Changed default weight of position to .1 and material to .8, since it seemed to drop pawns for better mobility.