Sadler's Wells, LondonThe choreographer brings comedy, carnival and African dance to a hallowed classic, and ends up with something totally newBlack and white; good and evil; reality and illusion. It's easy to reduce Swan Lake to a set of diametric opposites, and very easy for certain kinds of choreographers to reinterpret the ballet according to their own agendas. But Dada Masilo's new version stands apart from so m…