Posted on “Mary Oliver: Saved By The Beauty Of The World,” directed by Sasha Waters, opens at IFC Center July 3rd. Poetry and documentary can work at cross purposes. On the surface, Sasha Waters’ “Mary Oliver: Saved By The Beauty Of The World” is a straightforward, biographical account of its subject’s life. It’s full of talking heads interviews and celebrities reading the lesbian poet’s verses. Yet much of the film pulls against this impulse.