Ibragim Todashev, 26, an ethnic Chechen man who knew Tamerlan Tsarnaev, the dead Boston bombing suspect, was fatally shot Tuesday in Orlando, Fla., by an unidentified FBI agent. The agent had questioned Ibragim’s friend, Khusen Taramov, earlier in the day allowing him to leave. When he returned later, he found Ibragim had been shot dead . . .