NANCY DANCER DIED ON FEBRUARY 13, 1978. THAT WAS ONLY THE BEGINNING. With only five films, New Orleans-based writer/producer/director Jack Weis became one of the most enigmatic figures in '70s exploitation. And for his final trashterpiece, Weis delivered a filth-fueled, disco-drenched and gore-soaked epic of butchered hookers, hard-boiled homicide cops and a prissy psycho with