Scottish Opera’s new production of Britten’s A Midsummer Night’s Dream seems to open in midwinter. Snow falls, fairies hurl snowballs and the aurora borealis flickers and arcs across the darkened sky. Meanwhile Britten’s score swoons and sighs, its drowsy clouds of string tone wafting above gently snoring basses to create an atmosphere whose every glimmer evokes perfumed warmth.