The blackness is in the land, of course, the blight that’s reduced potatoes to asbestos, but, in Dublin Film Festival opener Black 47, it’s also in the hearts of the men who hold dominion over the land, and in the empire that produces them. Set in 1847, as crop failure and fever decimates the native Irish population, Lance Daly’s fourth feature reimagines the Great Irish Famine as a righteous revenge Western, a muddy, politically cynical chase thriller with shades of Rambo. James Frecheville stars as Michael Feeney, a Connacht man who returns home from overseas service in the British Army, to…