Sarah Kane was not your average playwright. Her works, which appeared on various London stages in the 1990s, featured rape, torture, and a man gnawing on infant corpses. She was despised by the theatrical establishment, but defended by some of theater’s luminaries. She killed herself at age 28. Assessing a legacy like that is the type of exercise for which few in the theater world have the stomach, but one Montreal director is determiend to try.