A story of tragedy, injustice and race. “Black Lives Matter” as a campaign and a modern activist movement began four years ago with resonance around the world. It highlights violence and systemic racism. But 23 years earlier there was no such movement or mouthpiece for those on the receiving end. Filmaker Yance Ford’s brother was fatally shot in 1992 and his latest film “Strong Island” is a powerful, personal and poignant exploration of the terrible consequences it had on him and his family.