A new horse racing track and casino proposed for Tinley Park has made it out of the starting gate. Overshadowed at Tuesday’s Illinois Racing Board meeting by uncertainty over the future of Arlington International Racecourse was the approval of a racing license for Playing in the Park LLC, which is now poised to open the state’s first new racetrack in nearly 75 years. The southwest suburban harness racing venture is headed by Hawthorne Race Course general manager Tim Carey and real estate developer Rick Heidner, who also runs one of the state’s largest video gambling machine companies.