message: [terminal] Line: adds rbegin/rend
diff: @@ -88,6 +88,7 @@ class Line
  using Storage = LineStorage<Cell>;
  using value_type = Cell;
  using iterator = typename InflatedBuffer::iterator;
  + using reverse_iterator = typename InflatedBuffer::reverse_iterator;
  using const_iterator = typename InflatedBuffer::const_iterator;
  Line(ColumnCount _width, LineFlags _flags, Cell _template = {}):
  @@ -228,6 +229,9 @@ class Line
  const_iterator begin() const noexcept { return buffer_.begin(); }
  const_iterator end() const noexcept { return std::next(buffer_.begin(), unbox<int>(columnsUsed())); }
  + reverse_iterator rbegin() noexcept { return buffer_.rbegin(); }
  + reverse_iterator rend() noexcept { return buffer_.rend(); }
  +
  Cell& front() noexcept { return buffer_.front(); }
  Cell const& front() const noexcept { return buffer_.front(); }
  