Don Cornelius, the creator of “Soul Train,” died Wednesday of a self-inflicted gunshot wound. He began his career as a  journalist who wrote passionately about the civil rights movement.   After noticing the lack of African American music on popular television, he created the Chicago-based show “Soul Train” in 1970 to showcase the funky blending of gospel and R&B that is soul music. It quickly gained an audience and went into syndication nationally a year later.  Celeste Headlee looks back on why “Soul Train” was groundbreaking and reflects on the may ways that Cornelius’ legacy lives on.