MonsterBy: John Gregory Dunne In Hollywood, screenwriters are a curse to be borne, and beating up on them is an industry blood sport. But in this ferociously funny and accurate account of life on the Hollywood food chain, it's a screenwriter who gets the last murderous laugh. That may be because the writer is John Gregory Dunne, who has written screenplays, along with novels and non fiction, for thirty years. In 1988 Dunne and his wife, Joan Didion, were