Merge pull request #9034 from sovrasov:mats_from_initializer_list

Add constructors taking initializer_list for some of OpenCV data types (#9034)

* Add a constructor taking initializer_list for Matx

* Add a constructor taking initializer list for Mat and Mat_

* Add one more method to initialize Mat to the corresponding tutorial

* Add a note how to initialize Matx

* CV_CXX_11->CV_CXX11

samples/cpp/tutorial_code/core/how_to_use_OpenCV_parallel_for_/how_to_use_OpenCV_parallel_for_.cpp

@@ -102,7 +102,7 @@ int main()
 
     double t1 = (double) getTickCount();
 
-    #ifdef CV_CXX_11
+    #ifdef CV_CXX11
 
     //! [mandelbrot-parallel-call-cxx11]
     parallel_for_(Range(0, mandelbrotImg.rows*mandelbrotImg.cols), [&](const Range& range){

samples/cpp/tutorial_code/core/mat_the_basic_image_container/mat_the_basic_image_container.cpp

@@ -58,7 +58,13 @@ int main(int,char**)
     Mat C = (Mat_<double>(3,3) << 0, -1, 0, -1, 5, -1, 0, -1, 0);
     cout << "C = " << endl << " " << C << endl << endl;
     //! [comma]
-
+    // do the same with initializer_list
+#ifdef CV_CXX11
+    //! [list]
+    C = (Mat_<double>({0, -1, 0, -1, 5, -1, 0, -1, 0})).reshape(3);
+    cout << "C = " << endl << " " << C << endl << endl;
+    //! [list]
+#endif
     //! [clone]
     Mat RowClone = C.row(1).clone();
     cout << "RowClone = " << endl << " " << RowClone << endl << endl;