Peter Shaffer's "Amadeus" is, at heart, a great love triangle. At one vortex, there's 18th century composer Antonio Salieri, wavering between piety and murderous peevishness. At another corner, there's the God whose favor Salieri craves, quite unrequitedly. And then, standing between them, Wolfgang Amadeus Mozart, God's true love, or at least it seems to Salieri [...]