In the freewheeling indie Sword of Trust, director Lynn Shelton has given her four talented principals the go-ahead to improvise when needed.  And with their background in comedy, the audience can clearly see these actors are game.  Shelton (who wrote this movie with former SNL staff writer Mike O’Brien) is no stranger to a loose narrative, as seen in 2009’s hilarious buddy comedy Hump Day.  But, this time, her reigns are a little too loose.