America’s favorite bespectacled aardvark put it best — “having fun isn’t hard when you’ve got a library card.” Arthur, the title character of author Marc Brown’s classic children’s book series and television show, might not have been talking about New Jersey libraries when he sang his “Library Card Song,” but he should have been. The state is filled with public municipal libraries — there are more than 400 central or branch locations, according to the New Jersey State Library — and most, if not all, have books, audiobooks and videos. Many municipal branches also offer museum passes and a pleth…