Agence France Presse: Hailed until only months ago as a silver bullet in the fight against global warming, biofuels are now accused of snatching food out of the mouths of the poor. Billions have been poured into developing sugar- and grain-based ethanol and biodiesel to help wean rich economies from their addiction to carbon-belching fossil fuels, the overwhelming source of man-made global warming. Heading the rush are the United States, Brazil and Canada, which are eagerly transforming corn, wheat, …