SPRINGFIELD — A three-judge federal court panel has upheld the legislative redistricting plan that Illinois lawmakers approved during a special session last summer, thus leaving in place the new maps that will govern state legislative elections for the next 10 years.In their 64-page opinion, released Dec. 30, the judges said the plaintiffs in the three separate lawsuits had failed to show that the redistricting plan violated federal law or the U.S. Constitution by diluting Latino voting power in Chicago and its surrounding …