Often the classic films the Charles Allis Art Museum screens are of the slightly obscure variety, but tonight’s selection is familiar to most film lovers: It’s Rebecca, the 1940 psychological thriller that won director Alfred Hitchcock his firstand, criminally, his onlyBest Picture Oscar. Joan Fontaine plays a young woman who marries a suave Laurence Olivier, but finds that his manor is haunted by the memory of his deceased first wife.