trailer for “Spencer” has the K-Stew fans feeling vindicated and the skeptics minding their tea and crumpets.Neon dropped the first official look at “Spencer” on Thursday, which showcases an almost wordless yet nonetheless compelling peek into Stewart’s performance as the beloved royal. “Spencer,” which was Diana’s maiden name before she wed the British royal, will center on the weekend in which Princess Di decided to leave her marriage to Prince Charles during Christmas 1991.She was always