MOSCOW (Reuters) - Russian President Vladimir Putin on Tuesday denounced Britain for making insulting demands that betrayed outdated colonial thinking, in comments likely to escalate a row over the murder of Alexander Litvinenko. Britain and Russia have each expelled four diplomats in a spat over the murder and Moscow's refusal to extradite the chief suspect in the case. "What they propose is an obvious vestige of colonial thinking," Putin was shown saying on Russian state television. "They must have clearly forgotten that Britain is no longer a colonial power, there are no colonies left and, thank God, Russia has never...