BOGOTA, Colombia (Reuters) - Colombian warlord Carlos Castano, whose disappearance has rocked peace talks between the government and far-right paramilitaries, has been strangled to death by former comrades, one of Castano's friends says. The outlaw Castano, who was political chief of the United Self-Defence Forces of Colombia, or AUC, went missing after a shootout with gunmen commanded by rival AUC chiefs at his hidden ranch in northern Colombia on April 16. "They caught Commander Carlos alive that very day and they killed him two days later, after they kept him for two days with his hands and legs bound,...