Barney Frank might not draw a connection between his coming out as gay nearly four decades ago and his coming out against left-wing dogmatism in the Democratic Party today. But the parallel is unmistakable: The 86-year-old former Democratic congressman from Massachusetts is shining a light on a sensitive subject that many people wish he would keep quiet about. In his forthcoming book, The Hard Path to Unity: Why We Must Reform the Left to Rescue Democracy , Frank contends that left-wingers have