Joe EskenaziGot lunch plans? Change 'em.Who are the patron saints of rummage book sales? So many to choose from -- but, then, there are so many saints. Leon Uris, James Michener, Tom Clancy, Tony Hillerman, Ed McBain, Robert Ludlum, Harold Robbins, the authors of Time-Life hardbacks (such as Reptiles, Patagonia, and Guns of the Old West) -- we could go on. Fittingly enough, the undisputed Jesus of this group is Dan Brown; there are always enough copies of The Da Vinci Code stacked up at second-h