By Ryan Fahey A schoolfriend of a teenager who knifed his teacher to death has spoken out a decade later. Ann Maguire, 61, was slaughtered by 15-year-oldWill Cornick when he pulled out a 34cm blade and plunged it into her back and neck seven times, severing her jugular vein, at Corpus Christi Catholic Colleage in Leeds on April 28, 2014. The well-loved Spanish teacher, who had worked at the school for 40 years, was murdered in front of a classroom-full of her stunned pupils. In 2014, Cornick’s trial heard how he had planned to murder three teachers, so brought two knives with him to school, in…