Chen Dance Center announces the next edition of its semi-annual choreographer's series "newsteps."   Choreographers are chosen at a public audition, judged by H.T. Chen, Walter Rutledge, Elizabeth Keen, and Lance Westergard.   Each receives a stipend, free rehearsal space, and three public performances at the Chen Dance Center.   Choreographers selected for the December performances are Keith Comley, Allison Plamondon, Lucas Klinge, Javier Padilla, Elisabeth Archer, and Caitlin Javech.