Performance work:   * '!obj' faster than 'obj === undefined'   * simplified loop for removing undefined edges in Cell.prepare()
Performance work:
  * '!obj' faster than 'obj === undefined'
  * simplified loop for removing undefined edges in Cell.prepare()

mbostock/Javascript-Voronoi,jjviscomi/Javascript-Voronoi,gorhill/Javascript-Voronoi,jjviscomi/Javascript-Voronoi,edrohler/Javascript-Voronoi,fabiantheblind/Illustrator-Javascript-Voronoi,gorhill/Javascript-Voronoi,edrohler/Javascript-Voronoi,gorhill/Javascript-Voronoi,edrohler/Javascript-Voronoi,fabiantheblind/Illustrator-Javascript-Voronoi,mbostock/Javascript-Voronoi,jjviscomi/Javascript-Voronoi