Alex Ross Perry is a filmmaker who should make us feel good about the altered state of American independent movies. He’s 27. He shoots in black-and-white on 16mm for, what to my eyes, is no money. He has ideas. He’s working outside the system. He’s what independent movies once were, idiosyncratic, creatively pure. His debut claimed to be an adaptation of “Gravity’s Rainbow.” It was called “Impolex,” shot on video, and was to “Gravity’s Rainbow” as snow peas are to snow.