Once upon a time, when documentaries consisted almost exclusively of “educational films,” inventors and presidents were usually the only people deemed worthy of the camera's attention. These days, thanks to cheap gear and the fragmentation of the culture, everybody's a potential subject for a nonfiction profile. S.F. DocFest has maintained those egalitarian, D.I.Y. principles throughout its rambunctious 11-year history, augmented with a special affection for art and artists.