SPRINGFIELD — Twenty-three years after a man died in prison, he was granted executive clemency by former Gov. Bruce Rauner, making this case the first posthumous exoneration in Illinois.On Tuesday, the Innocence Project — a nonprofit legal organization that works to exonerate wrongly convicted people — held a news conference at the state Capitol to celebrate the justice given to the man and push for more reform of the criminal justice system.In 1981, then 46-year-old Grover Thompson was wrongfully …