Halloween came to Sacramento early Wednesday morning as a group of six local science fiction lovers marched downtown dressed in Klingon, Death Star Trooper and Sith Lord costumes. Dozens of children and sci-fi fans flocked to take photographs and speak with the costumed characters. Others gawked, laughed and one child even cried as they meandered from the California Museum down K Street and past the Capitol to Cesar Chavez Plaza. The march was organized to promote The California Museum's new sci-fi exhibit "Out of this World: Extraordinary Costumes from Film and Television," which will run from Oct. 3 to Jan. 10. It will feature more than 50 props and costumes from some of Hollywood's mo