YANGON (AFP) - A United Nations special envoy flew to Myanmar Saturday, as the ruling junta deployed an overwhelming security presence in the nation's biggest city in a campaign to choke off mass protests. UN chief Ban Ki-moon has dispatched Ibrahim Gambari to broker talks between the military and its pro-democracy opponents, who have mounted two weeks of mass nationwide rallies. A violent operation to close down the demonstrations, which has run for four days and claimed at least 13 lives, appeared to have largely succeeded in deterring anti-government campaigners from returning to the streets. Downtown Yangon was largely deserted...