MovieMantz: In a movie season that’s overloaded with more superhero features than any other summer in previous years, “X-Men: First Class” is poised to stand out as the very best of the bunch. It’s definitely better than “Thor,” which kick-started the season on May 6, and, of course, the jury is still out on “Green Lantern” and “Captain America,” which don’t open until June 17 and July 22, respectively.