One of the mega-questions for world markets as 2013 swings into gear is whether China can recapture its economic mojo and pull multinational corporations selling everything from pig iron to pizza along with it. China bulls saw the mood shift a hair in their favor when official fourth-quarter growth accelerated to a 7.8% annual clip after seven straight quarters of demoralizing deceleration. But debate rages on noisily about whether the recovery will prove ephemeral or robust.   Some light may be thrown on the subject by the Q4 2012 earnings statements that are coming in bunches now from US-based ...