*(Crowd View, US Embassy Protection, Wide Angle Aerial View in front of Seoul City Hall an hour ago, General scenes)By Bill Tarrant (UPDATE) SEOUL (Reuters) - Tens of thousands of South Koreans railed against the U.S. military and mourned two girls killed by American soldiers in a road accident by holding a candle lit march that turned central Seoul into a sea of light on Saturday. Many in the crowd of mostly young people chanted slogans demanding a withdrawal of the U.S. military presence aimed at deterring aggression from North Korea, even as tensions rose with Pyongyang vowing earlier in...