Colombia president warns of plot to remove him as former ally calls him a drug 'addict' / Colombian authorities eliminate cartel leader behind presidential assassination plot / Colombian president aims to reduce drug violence and weaken rebels by paying farmers to switch crops / Cocaine is 'no worse than whiskey', says Colombia's president / Cocaine "no worse than whiskey," Colombia's president says / Colombia president welcomes 'compatriots' returned from US: 'The migrant is not a criminal' / Colombia president decrees emergency powers to restore order in coca region wracked by rebel combat