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

Improve the readability of the tutorial.

* change tutorial to use enum name instead of value

* use enum name instead of value

Use directly the doxygen snippet command for the Changing the contrast and brightness of an image tutorial. Extend the tutorial with a pratical example and with a gamma correction method to adjust the brightness of an image.

* GSoC 2016 - Adding toggle files to be used by tutorials.

Add a toggle option for tutorials.
* adds a button on the HTML tutorial pages to switch between blocks
* the default option is for languages: one can write a block
for C++ and another one for Python without re-writing the tutorial

Add aliases to the doxyfile.
* adding alises to make a link to previous and next tutorial.
* adding alias to specify the toggle options in the tutorials index.
* adding alias to add a youtube video directly from link.

Add a sample tutorial (mat_mask_opertaions) using the developed aliases:
* youtube alias
* previous and next tutorial alias
* buttons
* languages info for tutorial table of content
* code referances with snippets (and associated sample code files)

* Removing the automatic ordering.
Adding specific toggles for cpp, java and python.
Move all the code to the footer / header and Doxyfile.
Updating documentation.

Fixed difference in the given arguments to the ellipse function and the description after that

Fixed two more typos

Replaced unnecessary the with to

Conflicts:
	doc/tutorials/core/adding_images/adding_images.markdown
	doc/tutorials/core/basic_geometric_drawing/basic_geometric_drawing.markdown
	doc/tutorials/core/random_generator_and_text/random_generator_and_text.markdown
	modules/imgproc/include/opencv2/imgproc.hpp

Fixed difference in the given arguments to the ellipse function and the description after that

Fixed two more typos

Replaced unnecessary the with to