Former U.S. Sen. Adlai Stevenson III of Illinois has died at his home on Chicago’s North Side. He was 90.His son Adlai Stevenson IV, who confirmed the Illinois Democrat’s death, said his father had dementia, the Chicago Sun-Times reported.Before his health declined, Mr. Stevenson kept active organizing presentations and speakers for the Adlai Stevenson Center on Democracy in Libertyville, Illinois. He also worked on the family farm in Hanover, Illinois, raising cattle, growing corn and hay for their feed, and …