Marc Malkin Senior Film Awards, Events & Lifestyle EditorKristen Stewart wants you to know that “Spencer,” her new movie in which she stars as Princess Diana, is not a biopic or documentary. It is a fictional take on what happened when Diana decided during a family Christmas that she wanted out of her marriage to Prince Charles.“We’re not trying to educate anyone, we’re not trying to solve anything,” Stewart told me Tuesday night at the film’s Los Angeles premiere at the DGA.