// Move bits
// Higher priority moves have higher ulong value.
// 6 6 6 6 5 5 5 5 5 5 5 5 5 5 4 4 4 4 4 4 4 4 4 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0
// 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
// B|CapV   |CapA   |Promo  |Kil|History                                                  |C|K|E|D|P|Q|From         |To           
// B =     Best Move
// CapV =  Capture Victim
// CapA =  Capture Attacker (inverted)
// Promo = Promoted Piece
// Kil  =  Killer Move
// C =     Castling
// K =     King Move
// E =     En Passant Capture
// D =     Double Pawn Move
// P =     Pawn Move
// Q =     Quiet (not capture, castling, or pawn promotion)
// From =  From (needs one extra bit for illegal square)
// To =    To (needs one extra bit for illegal square)