The Atlanta Film Festival burst into action last weekend, with the much heralded Matthew McConaughey starrer “Mud,” a funny, touching ensemble comedy called “Claire’s Cambodia,” and a sneak preview of the Sundance Channel’s first original, scripted series, “Rectify,” which was created by Georgia’s own Ray McKinnon and films in Griffin. As always, between the higher profile films the 2013 festival intersperses dozens of features and shorts that may come with less fanfare but frequently surprise. The festival looks to close strongly, too.