message: fix calling data members
diff: @@ -114,7 +114,7 @@ public:
  *
  * @return the column indexes of the matrix.
  */
  - index_type *get_col_idxs() noexcept { return this->col_idxs_.get_data(); }
  + index_type *get_col_idxs() noexcept { return col_idxs_.get_data(); }
  /**
  * @copydoc Ell::get_col_idxs()
  @@ -125,7 +125,7 @@ public:
  */
  const index_type *get_const_col_idxs() const noexcept
  {
  - return this->col_idxs_.get_const_data();
  + return col_idxs_.get_const_data();
  }
  /**
  @@ -157,7 +157,7 @@ public:
  */
  value_type &val_at(size_type row, size_type idx) noexcept
  {
  - return this->values_.get_data()[this->linearize_index(row, idx)];
  + return values_.get_data()[this->linearize_index(row, idx)];
  }
  /**
  @@ -165,7 +165,7 @@ public:
  */
  value_type val_at(size_type row, size_type idx) const noexcept
  {
  - return this->values_.get_const_data()[this->linearize_index(row, idx)];
  + return values_.get_const_data()[this->linearize_index(row, idx)];
  }
  /**
  @@ -255,7 +255,7 @@ protected:
  size_type linearize_index(size_type row, size_type col) const noexcept
  {
  - return row + this->padding_ * col;
  + return row + padding_ * col;
  }
  private:
  