It was a cold day in March, even for Chicago, but the sky was a bright blue, and the frigid winds embraced the city as it has done for hundreds of years. A brisk 18 degrees above zero was not the best day to be house hunting, but this family of five huddled into a luxury Mercedes sedan, braving the cold to find a much-needed new home. “Yes, that’s it up ahead. East Townline Road, route 60. Take that exit and go east toward Lake Forest,” said the adult woman sitting in t