Usually, street closures around the Capitol hail the arrival of one of Austin's many street festivals, where you can listen to a wishy-washy blues-rocker do his best to channel Stevie Ray Vaughn while you eat a turkey leg amongst a sea of fanny-packed families and homemade jewelry vendors. But once a year it means it's Texas Book Festival time. As literary events go in this town, it is the big one. For two days......