fix board.go bugs

board.go

@@ -71,7 +71,7 @@ func (b *Board) isSquareAttacked(pos Position, byColor int) bool {
 	r, c := pos.Row, pos.Col
 	pawnDir := 1
 	if byColor == Black {
-		pawnDir = -1
+		pawnDir = 1
 	}
 	for dc := -1; dc <= 1; dc += 2 {
 		nr, nc := r-pawnDir, c+dc
@@ -199,7 +199,7 @@ func (b *Board) pawnMoves(from Position, color int) []Move {
 	r, c := from.Row, from.Col
 	dir := 1
 	if color == Black {
-		dir = -1
+		dir = 1
 	}
 	nr := r + dir
 	if b.inBounds(nr, c) && b.Grid[nr][c].Piece == Empty {