Steven Spielberg’s big-screen adaptation of “The Adventures of Tintin: The Secret of the Unicorn” is in the postproduction stage—yet another sign that the appeal of Belgian cartoonist Hergé‘s Tintin is as timeless as his globe-trotting perma-adolescent wunderkind. However, as Pierre Assouline points out in his new book “Hergé: The Man Who Created Tintin,” Tintin led a far more colorful life than his creator (born Georges Remi) did.