In New York City, tomorrow is Primary Day, when the crowded field of candidates vying for Mayor, City Council, and the five borough presidencies (among other offices) gets tighter as voters select those who will make it to the general ballot. For registered Democrats in the Big apple, there’s something new this year, too: ranked-choice voting. Instead of choosing a single candidate, constituents can vote for all of them in order of preference. In theory, this…