Confidence. Set in 1960s Oklahoma, Martha Stephens’s movie To the Stars is an easy coming-of-age drama that feels as if it is from a bygone period. Iris (Kara Hayward), whose unhappy home life leaves her feeling as if she’s an outsider in school, has her world upended when a brand new woman named Maggie (Liana Liberato) comes to city. Maggie is vivacious and friendly, regardless of the rumors the other women whisper about her, and she and Iris turn into unlikely buddies. To the Stars lags a bit in spots — a number of the performances are uneven, while others…