POLITICAL talks on Libya's future have reached agreement on holding elections within 18 months, the United Nations acting Libya envoy has announced, hailing a "breakthrough" in a peacemaking process that still faces great obstacles. "There's real momentum and that's what we need to focus on and encourage," envoy Stephanie Williams said at a news conference in Tunis, where 75 Libyan participants chosen by the United Nations have been meeting since Monday. The meeting has reached preliminary agreement on a roadmap to "free, fair, inclusive and credible parliamentary and presidential elections" that also includes steps to unite institutions, she said. Libya…