By THE PULSE NEWS MEXICO STAFF It has been 45 years since the residents of San Miguel del Milagro, in the central Mexican state of Tlaxcala, first discovered the some of the nation’s oldest pre-Hispanic murals in the archeological site of Cacaxtla. Shrouded in mystery, the centuries-old ruins in Tlaxcala’s volcanic valley is one of Mexico’s greatest pre-Columbian mysteries, with