Cultural diversity is uncritically celebrated in the classroom, while our Anglo-Celtic heritage is thoroughly repudiated, writes Kevin Donnelly.If there is one positive thing to come out of the violence in Cronulla, it will be a long hard look at how schoolchildren are educated about Australian culture and what they are taught about their responsibilities as members of a civil society.Judged by the age of many of those involved in abusing women, the mob violence at Cronulla beach and the subsequ…