Civil-rights activist the Rev. Jesse Jackson took the microphone shortly before noon today at the Macedonia Missionary Baptist Church in Eatonville and pronounced slain teen-ager Trayvon Martin to be a martyr. "Martyrs have power," Jackson said near the end of his hour-long sermon. "He represents all of us." Dressed in a dark gray suit and blue tie, Jackson began his address with a chant: "Stop the violence. Save the Children. Keep hope alive!" "How do we go from a moment to a movement that creates fundamental change," Jackson asked the capacity crowd, estimated at 1,600 people. "If it's a moment,...