When a popular new idea takes root, it can quickly grow wild, encompassing all in its path and overcoming whatever obstacles that get in its way. That’s true for the notions underlying everything from new consumer products to Internet web sites to social movements. One of those crusades that got off to a rough start but blossomed once its viability gained broad support was the American civil rights movement, a cause profiled in the historical drama, “Lee Daniels’ The Butler,” the immensely popular late summer release that’s returning to theaters December 6.