CHICAGO (Reuters) - First lady Michelle Obama on Saturday will attend the funeral of a Chicago girl whose slaying days after she performed at the presidential inauguration in Washington added to the heightened national attention to the toll from gun violence. Hadiya Pendleton, 15, was fatally shot on January 29 as she and her friends shielded themselves from rain under a canopy in a Chicago park in what police say was a case of mistaken identity in a gang turf war. Pendleton, a sophomore at Martin Luther King Jr. ...