For more than a year, oil diplomats have been busy behind the scenes trying to forge a deal between OPEC and nations outside the cartel to revive prices by curbing output. The maneuvering, led first by Algeria and now Qatar, started to bear fruit Tuesday, when Russia and Saudi Arabia, at odds over the war in Syria, agreed to freeze production at January levels. The first public one-on-one meeting between the oil chiefs of the two largest producers in eight months essentially suspended a war for market share and capped months of secret talks, people familiar with the matter said. […]