Yaël Farber’s Macbeth sets out to be a great work of art. The director crams the Almeida’s stage with suggestive props, glass panels, microphones, a wheelbarrow full of jackboots. The witches are not the usual vagrants or carbuncled mystics. These grim-looking ladies have expensive hairdos and nicely ironed shirts — like a panel of disgruntled academics at a tribunal.