Hilary Swift / The New York Times file photoMaine Gov. Paul LePage has twice been elected in three-way races with less than a majority of the vote. But now, Maine has changed how it will choose most officeholders, becoming the first state in the country to adopt ranked-choice voting, also known as instant-runoff voting, which allows voters to list candidates in order of preference so that if in the first round no one wins a majority, officials can recount the ballots immediately until someone does.