Be warned: The Texas Chain Saw Massacre is back, after seven years, in a major re-release. Slightly more restrained than its title suggests, it's still a nonstop shocker, climaxing in a scene of cruelty so chaotic and prolonged that even the chief villain wants to leave the room. While the film has elements of parody aimed at accepted middle- class conventions, its own sadism and sexism are equally revealing. Yet filmmaker Tobe Hooper has a lot of talent, reflected in the lofty reputation he has acquired among some critics who specialize in this sort of thing. Neither the talent nor the reputation has paid off in his latest picture, "The Fun House" -- so when is he going to leave "shoxploitation" behind a nd make a real movie?