Affordability, outdoor living, and abundant wildlife attract retirees to this historic town.Blue skies and clear waters at the Ellie Schiller Homosassa Springs Wildlife State Park.Credit: Michael Warren/Getty ImagesFlorida’s "Nature Coast" is a quieter, more laid-back alternative to the state's buzzy stretches of coastline. It spans almost a million acres along the Gulf, where the main draw is its forests, over 100 parks and preserves, and river…