Bloomberg: A major threat to fossil fuel companies has suddenly moved from the fringe to center stage with a dramatic announcement by Germanys biggest power company and an intriguing letter from the Bank of England. A growing minority of investors and regulators are probing the possibility that untapped deposits of oil, gas and coal -- valued at trillions of dollars globally -- could become stranded assets as governments adopt more rigorous climate-change policies. The concept gaining traction from Wall...