Chicago’s hip-hop community is in a war of words that has escalated into violence, with the shooting death of a teenage rapper. Tuesday was another night, another homicide in a year in which hundreds of Chicagoans have been gunned down; the murder rate for the year’s first half is up an alarming 38 percent over last year. This time the victim was Joseph Coleman (18-year-old rapper Lil Jojo). The bicycle-riding teen was slain by a drive-by shooter in his South Side Englewood neighborhood. His death starkly punctuated a gang-related war of words and music between Jojo and rapper Lil Reese,...