Director Bryan Singer’s reinvention of “Jack and the Beanstalk” was a disappointment at the box office, a fact that probably has more to do with the concept than the execution. Although a fairy tale, the movie is presented as a big-budget, special-effects blockbuster that plays as much like “Clash of the Titans” as a Disney cartoon. That places a lot of limitations on audience.    Teens and young adults don’t typically line up for fairy tales, yet “Jack” has a dark tone that may concern parents of younger children.