An elaborately plotted, carefully produced spectacular of a film, this Satanist - oriented, Lysastratesque Exxie may be America's next 'Deep Throat.' 'Devil's Due' is one of the new-style movies, handsomely mounted full-length features with beautiful color and a real plot line. Its producers are eminently civilized people with lots of experience in Italian cinema. In a way they and serious producers like them are establishing a new kind of star system, of which Cindy West, Linda Lovelace and a few other tasties are outstanding examples.