message: Allow modifying underlying ArrayView in ViewIndirection
diff: @@ -292,7 +292,8 @@ struct ViewIndirection
  ViewIndirection(IndirectionBufferType buf = {}) : m_vecBuf(buf) { }
  - IndirectionBufferType data() const { return m_vecBuf; }
  + IndirectionBufferType& data() { return m_vecBuf; }
  + const IndirectionBufferType& data() const { return m_vecBuf; }
  inline ConstIndirectionResult indirection(PositionType pos) const
  {
  