You have a one-shot chance tonight to see one of the best movie fantasies ever made. "Stairway to Heaven" is about a wartime British flyer who is shuttled about a bit by heavenly bureaucracy; it combines quietly plausible acting with some spectacularly implausible technicolor photography. Kim Hunter is very pretty, and Stairway's heavenly stairway is one of a spate of remarkable sets. It is no movie to miss