Students, after years in politically correct classrooms, leave school cynical and suspicious, writes Kevin Donnelly.Has political correctness gone too far? We have all got examples: a fat person becomes a “person of substance”, stupid people are described as “cerebrally challenged” and drunks and drug addicts are described as “substance abuse survivors”.The problem is not just restricted to language. According to the Australian Senate, our schools and universities are also at risk.Last week…