A crowd of heart-broken mourners bid a final, tearful farewell Saturday to eight children killed in a predawn mass shooting carried out last month in Shreveport, La., by the father of most of the victims. Led by a procession of grieving families and eight white caskets, the service at Summer Grove Baptist Church centered on a raw sermon from Pastor Kim Burrell, who reminded those searching for answers that even in the face of the unthinkable, “God is still on the throne.” “To ask the question, ‘