In all seventy-six minutes of Benjamin Ree’s new documentary “Magnus” I’m not sure if I can remember ever seeing Magnus Carlsen, the world’s highest ranked chess player, ever smiling during a game. He smiles plenty when he wins, but that’s not the same. During the games his eyes scrunch up and his face tightens into a mask of marbled concentration. The happiest we ever see him is when he tears himself away from the obsession that