BONN (Reuters) – A former banker was handed a 3-1/2 year jail sentence on Wednesday for his part in Germany’s biggest post-war fraud, a scam that involved scores of banks and investors engineering multi-billion-euro trades to make bogus tax claims. The banker, identified as Detlef M., in line with court reporting practices in Germany, is a former employee of M.M. Warburg group, part-owned by one of Germany’s oldest banking dynasties. He is the second person to receive a jail sentence for trading activity that thrived during the years after the financial crash and cost Germany more than five bi…