Christine King Farris, the last living sibling of the Rev. Martin Luther King Jr., has died.Her niece, the Rev. Bernice King, tweeted that her “beloved aunt” died Thursday. She was 95.For decades after her brother's assassination in 1968, Farris worked along with his widow, Coretta Scott King, to preserve and promote his legacy. But unlike her high-profile sister-in-law, Farris' activism — and grief — was often behind the scenes.“She may not have always been on the line of the march, but that was true with a lot of the heroes of the Civil Rights Movement,” said Marcellus Barksdale, a history professor at Morehouse College,…