SPRINGFIELD — The state’s high court is set to issue its first batch of opinions of the new year.On Friday, the Illinois Supreme Court is expected to weigh in on Chicago’s use tax for rental cars, the firings of a school superintendent and a police officer as well as a post-conviction plea for a man found guilty of a murder more than a decade ago.The city tax case and the police officer firing case were argued in September. The other two cases were argued in November.An appeals court in 2015 upheld the …