By Simon Gardner CATEMACO, Mexico (Reuters) – Fiery Mexican leftist Andres Manuel Lopez Obrador has vowed to stop the government's energy and tax reforms and hopes to lead even bigger protests than when he brought central Mexico City to a standstill after narrowly losing the 2006 presidential election. A colorful renegade and a former Mexico City mayor, Lopez Obrador accuses President Enrique Pena Nieto of trying to sell off Mexico's assets by seeking to lure foreign capital into the state-controlled energy sector. …