In the last two years, the city's Board of Aldermen have taken hundreds of final votes on matters big and small, including plans to finance a new football stadium, to put a soccer stadium before voters, to increase the minimum wage and to approve countless tax incentive plans for developments of all sizes. But only once in all those instances has Alderwoman Lyda Krewson voted no — on a plan opposed by neighbors to vacate a single downtown block.…