Former GOP gubernatorial candidate Charlie Baker flatly ruled out a run for the special Senate election, saying he doesn’t “really think of myself as a senator,”but he urged his former boss and former Gov. William Weld to jump into the fray should Scott Brown decide to stay out of the race. The Swampscott Republican has kept out of the media limelight since losing his 2010 bid for governor. Both U.S. representatives Edward J. Markey and Stephen F. Lynch have entered the race on the Democratic side, but so far Brown, who just lost to U.S. Sen. Elizabeth Warren last fall,...