Are you 12 years old? Have you ever been 12 years old? Are you planning to be 12 years old at some point in the future? If so, then this is the film for you. “A Dozen Summers” is a comedy about what it’s really like to grow up in the 21st century. Get ready to enter the world of Maisie and Daisy McCormack, twin sisters who have just hijacked a children’s film in order to tell their own story. Or possibly one about a ghost girl who eats teachers. They haven’t decided yet.