Hubert Selby Jr., Brooklyn-born ex-merchant mariner who turned to drugs and writing after cheating death, created a lasting vision of urban hell in his novel ''Last Exit to Brooklyn," a critical success and a controversial best-seller. Before the book's publication in 1964, Selby had earned less than $100 writing, and afterward he derailed himself with a drug habit. His writing gained a passionate following in Europe, was forgotten in the US, and...