The writer-director talks about his new film, co-starring Denzel Washington, and reveals how it felt to work without his brother, Ethan, for the first time in nearly 40 years It might be the unlucky play for British theatre rep types. But for movie directors, Macbeth has been a talisman, a fascinating and liberating challenge " for Akira Kurosawa, with his version, Throne of Blood; for Roman Polanski; and for Justin …