public void Set(Position pos)
 {
     m_x = pos.m_x;
     m_y = pos.m_y;
 }
 public Position(Position pos)
 {
     Set(pos);
 }
 public bool Equals(Position pos)
 {
     return m_x == pos.m_x
         && m_y == pos.m_y;
 }
        Position m_from;      // position to move from

        //Piece m_captured;

        public ChessMove(int r, int c, int _r, int _c)
        {
            m_from = new Position(r, c);
            m_to = new Position(_r, _c);
        }