message: Fix the documentation for Mat::diag(int).
  * Fix the documentation for Mat::diag(int).
  Fix issue
  * Fix the documentation for Mat::diag(int).
  Fix issue
  * Add support for printing out cv::Complex.
  * Remove extra spaces.
  * cv::Complex is submitted as a new pull request.
diff: @@ -1081,9 +1081,9 @@ public:
  single-column matrix. Similarly to Mat::row and Mat::col, this is an O(1) operation.
  @param d index of the diagonal, with the following values:
  - `d=0` is the main diagonal.
  - - `d>0` is a diagonal from the lower half. For example, d=1 means the diagonal is set
  + - `d<0` is a diagonal from the lower half. For example, d=-1 means the diagonal is set
  immediately below the main one.
  - - `d<0` is a diagonal from the upper half. For example, d=-1 means the diagonal is set
  + - `d>0` is a diagonal from the upper half. For example, d=1 means the diagonal is set
  immediately above the main one.
  */
  Mat diag(int d=0) const;
  