SPRINGFIELD — When it comes to ongoing state pension litigation, the opposing sides don’t agree on many of the legal issues. But the expedited schedule approved by the high court this week setting oral arguments in the case for March is perhaps as close to a compromise as possible. The Illinois Supreme Court has approved a timetable that gives the state until Jan. 12 to file the first substantive briefs in the case, then gives the plaintiffs until Feb. 16 for a reply. Oral arguments will be about a …