Writer-director Sean Wang is tough on himself in “Dìdi,” a fresh and funny summer-before-freshman-year flashback that provides an Asian American angle on that Sundanciest of indie-film genres: the semi-autobiographical coming-of-age movie. In what feels like a cross between Bing Liu’s “Minding the Gap” and Jonah Hill’s “mid90s” — courtesy of the young director’s teenage desire […]