By Joshua Schneyer and Swetha Gopinath (Reuters) - Dow Chemical’s chief executive Andrew Liveris, fresh from orchestrating a $130 billion merger with U.S. rival DuPont, on Tuesday announced plans to retire by mid-2017, a step he takes after years of pitched battles with an activist shareholder unhappy with his leadership. On a quarterly earnings call with analysts, Liveris said he would step aside by the second half of next year. The news represents a victory for Daniel Loeb, the head of New York hedge fund Third Point. The fund has a 2 percent stake in Dow and Loeb has been...