Interfor Corp. says it plans to cut production by about 20 percent across its sawmills in the B.C. Interior as it faces declining lumber prices and higher log costs.  The Vancouver-based company says the scale-back is a temporary measure planned for the fourth quarter.  It says the cuts will be achieved through reduced operating days and extended weekends and holiday breaks spread across its three mills in the Interior.  Lumber prices for Western softwood have plunged from over US$650 per thousand board feet in June to under US$400 as ...