A father of four was stabbed to death by a deranged childhood classmate over a long-festering grudge, with the killer snapping photos of his victim before the slaying inside a Brooklyn bodega, police and family members said Wednesday. Severiano “John” Reyes, 36 was hanging out with relatives on Roebling St. near South 9th St. in Williamsburg about 8:30 p.m. Tuesday when the old schoolmate ...