LimaThe trial date for the only adult charged in the slaying of a teenager last summer has been moved to Aug. 29. Xavier Arrick, 19, also has a final pretrial hearing scheduled for Aug. 10. He is charged with complicity to murder with a gun. Officials said he was the driver in the Aug. 30 slaying of 16-year-old Eric Armstead, who was shot once in the head and died while sitting on a porch at 620 Madison Ave.The shooting stemmed from a feud between two groups. Police said Arrick was one of five teens in the car. The shooter, Dederic Matthews Jr., who was 14 at the time of the shooting, was sentenced last week to 13 years prison on the charge of involuntary manslaughter.