DENVER - Thousands of illegal immigrants and their allies across the country plan a show of force Monday to illustrate how much immigrants matter in the U.S. economy. Some will skip work, others will protest at lunch breaks, school walkouts or at rallies after work. There are planned church services, candlelight vigils, picnics and human chains. Hector Castillo, a Denver baker usually keeps his doors open 360 days a year. But anybody looking for his Mexican pastries or cookies will be out of luck Monday when Castillo plans to close his doors in sympathy with immigrants. For Castillo, 45, it's...