Choreographer David Parker, has gleefully cracked the old chestnut open, roasted it with tap riffs, vaudeville turns, ballet steps, disco, contemporary dance, toe-tapping and rebuilt it into a seasonal fixture for 21st century New York City--a tonic for cheerful grinches and latter-day snow angels.   With genre-nonconforming glee, Parker and The Bang Group purge the show of the saccharine and shake loose its tinsel.  In fact, the only traditional thread is Tchaikovsky's music but that too takes a turn off center as portions of the original score are juxtaposed with arrangements by Duke Ellington, Glenn Miller and Fred Waring and The Pennsylvanians.  Passionately non-traditional, Nut/Cracked is as ardent and virtuosic as it is disruptive. Its rhythmic component is vigorous with a stomp-off on bubble wrap, tap dances on pointe, barefoot hoofing, and a Waltz of the Snowflakes featuring precision body slams in 3/4 time. Yet the show retains a sense of…