When you aim to remake “Dallas,” partner, you’re putting on a big hat. But TNT and the producers of Dallas 2.0, which launches with back-to-back episodes Wednesday night, have the cattle to do it. They start with the smart move of bringing back the original Ewing brothers, Larry Hagman’s J.R. and Patrick Duffy's Bobby. Then they make the smarter move of not pretending this old guard would still be dominating the world of Southfork Ranch, as if no descendant of this screwed-up family had ambitions of his or her own, good or evil. Instead, the producers simply let the gene...