MGM is showing tonight, as a double feature, two of the strangest, most inventive vampire movies ever made – and both of these movies reward diehard film fans, who are aware that the vampire, in cinema lore, goes back to German director F.W. Murnau’s 1922 silent classic, Nosferatu. That movie was based, in large part, on the Bram Stoker novel Dracula, a decade before Hollywood cast Bela Lugosi as the long-toothed count. In Nosferatu, Max Schrek played the mysterious, ratlike Graf Orl