Slightly Less Beloved Classics takes a second look at the lesser-known works of celebrated authors. Here we shall decide what is to remain by the wayside and what is to be led gaily back home, lauded with timbrels and trumpets and fatted calves. Previously in this series: Nightingale Wood.  A Canticle for Leibowitz is the kind of book that, if you have read it and you see it on a bookshelf at someone else's house,…