Just when you think you’ve seen everything, you get the following: the next leader of China, a nation of 1.3 billion people vying to supplant the United States as the world’s largest economy, flies to America on a goodwill tour and goes to…a farm in Iowa. Yes, Vice President Xi Jinping will spend the evening in Muscatine, Iowa, in the Victorian farmhouse he briefly lived in more than a quarter century ago, when he was an official from the Chinese province of Hebei sent to learn Iowa’s agricultural innovations and bring them back to a China that was then struggling to increase crop yields