The Bang Group returns for its 16th season of "Nut/Cracked," its comic, neo-vaudeville version of the holiday classic, performed by and ensemble of 21 dancers joined by guest students from The Dalton School, Frank Sinatra H.S. for the P.A., and e.g. dance.   Choreographer David Parker's choreography is totally unpredictable as he whisks together an array of dance forms, from tap to pointe, inspired by competition, intoxication, greed, Chinese take-out, bubble-wrap, and more.   Musically, the choreographer takes an equally playful approach with the traditional Tchaikovsky orchestration along with renderings by Duke Ellington and Glenn Miller.   A one-hour delight for all ages.