RIVERSIDE A 16-year-old Riverside boy doing stunts in a high school parking lot crashed his new 2008 Yamaha R1 motorcycle into a classroom building, and died a short time later, Riverside police said Sunday. Coroner's officials identified the teen as Austin Lee Allen, 16, of Riverside. Riverside police Sgt. Dan Reeves said the motorcycle rider was initially believed to be a student at Martin Luther King Jr. High School, where the crash was reported at 7:22 p.m. Saturday. Witnesses said Allen was riding the Yamaha alone in a parking lot at the school, in the 9300 block of Wood Road...