NOT even Boeing could deny that airbus has had a barnstormer of a week at the Paris air Show, racking up record orders day after day.  airbus executives have been stunned by the huge success of the fuel-efficient a320neo (an acronym for "new engine option"), which the European plane maker had deliberated for years whether to bother building.  The only thing missing for airbus this week was a substantial agreement with an airline to buy a batch of a380s - the European company's flagship and the world's biggest passenger plane.  The a380, after all, did not have the best start to the week - one of the enormous wings of the demonstration plane had a close encounter with a building as it taxied into the show on Sund