Friends and colleagues of Ed Bullins, a leading Black playwright of the 1960s, whose work helped shape a protest movement within the theater centered on the African American experience, remember the former Northeastern University professor as gentle, warm, and restlessly prolific.  Bullins passed away on Nov. 13 from complications of dementia. He was 86. “I found him to be very warm,” says Richard O’Bryant, the head of Northeastern’s John D. O’Bryant African American Institute. “He came from the ’60s and was a product of the civil rights movement. Of course, they carried that struggle on their sleeve, and he very much enjoyed talking about it.” O’Bryant says Bullins was deeply…