PHILADELPHIA, PA. (AP) .- Posting comments via Facebook or Twitter seems faster than a speeding bullet, but DC Comics is going back to its Silver and Bronze Age ways, returning readers’ letters to the pages of its comic books. The New York-based publisher — its imprints also include Vertigo and Mad Magazine — used to devote a single page, typically toward the back, to letters from readers commenting on the latest adventures of the Justice League, Batman, Superman and scores of other characters. Letters pages were once common in comic books and gave far-flung readers the chance to weigh in on stories, heroes, villains