What if an American ballerina quintet was dropped into a mob flick in Central Europe? Director Vicky Jewson answers this question in “ Pretty Lethal ,” at first with aplomb, but eventually with all the follies this setting implies, and few of the imaginative strengths. The film does a small handful of things rather well, so it does each them more than once, from repeated action beats, to popular needle drops about dancing (“Rhythm is a Dancer,” “Everybody Dance Now”) whether or not they tonally