After percolating in federal court for nearly two years, a constitutional challenge to Illinois’ same-day voter registration statute has been dropped.A conservative legal group had tried to upend a law that allows Illinois voters to register and cast ballots on Election Day. They had argued it discriminates against rural voters because it mainly applied to counties with more than 100,000 people.But the parties in the suit agreed to end the dispute with the law still standing. A judge in the case signed off on an …