Mike Martin is stepping down as Denver-based chancellor of the Colorado State University System after less than three years in the post. "For both personal and professional reasons, it's time for me to wind down my long career in higher education," said Martin, who was named to the post in May 2012, in a statement released by the CSU System. Martin will exit as chancellor March 1 but will move into a part-time role as chancellor emeritus and senior fellow, focusing on "issues related to the future…