The recent spate of shootings in Boston has citizens nervous about safety, and none has shaken the community like the daylight killing of Luis Troncoso, a 20-year-old Dorchester father of two who was shot in the head while playing basketball in a quiet Jamaica Plain park. Yesterday, Boston Police Commissioner Edward Davis toured JP's Centre Street in an effort to reassure business owners and citizens that increased police foot patrols will curb the violence. "We......