private void OnTriggerEnter2D(Collider2D collision)
    {
        GameObject square = collision.gameObject;

        bool bad = square.GetComponent <SquareProperties>().bad;

        if (bad)
        {
            if (!GameMaster.invincible)
            {
                GameMaster.Lose();
            }
        }
        else
        {
            Destroy(square);
            GameMaster.AddToScore(10);
            this.transform.localScale += new Vector3(growthPerSquare, growthPerSquare, growthPerSquare);
            GameMaster.AddToSpeed(speedPerSquare);
        }
    }