The Enoch Pratt central library was designed nine decades ago to beckon passersby, and not alienate them from the knowledge within its walls. Now, after a sweeping renovation, there will be a huge party this weekend to welcome visitors back and celebrate its grand reopening.We talk with Heidi Daniel, president and CEO of the Pratt, about how libraries are changing. Plus, Carla DuPree, executive director of City Lit Project, talks about the books that have changed her life.