Campaign Buttons, by JSF539 via Flickr The election trail continues to heat up for Barack Obama and Hillary Clinton, as four looming primaries in the next couple of weeks could go a long way toward deciding the nominee. On Tuesday, voters in Wisconsin and Hawaii will go to the polls and on March 4, Texans and Ohio-ans will do the same. How are things shaping up? On Saturday, the Houston Chronicle endorsed Barack Obama. In......