Seen yesterday in Cunningham, the new Merce Cunningham documentary shot in 3-D by writer/director Alla Kovgan: imagery and brief excepts from “Summerspace,” the choreographer’s legendary ‘no-center’ ballet dating from 1958 and performed in Robert Rauschenberg’s pointillist costumes/decor to music by Morton Feldman. The film, which may bring the rarefied artist his most widespread exposure with ...