GSoC 2016 - Adding ALIASES for tutorial (#7041)

* 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.

doc/tutorials/introduction/documenting_opencv/documentation_tutorial.markdown

@@ -439,6 +439,83 @@ Then include this snippet into documentation:
 compatibility with the old rST documentation. But newly created samples should be included with the
 _snippet_ command, since this method is less affected by the changes in processed file.
 
+### Toggle buttons inclusion commands {#tutorial_documentation_toggle_buttons_commands_include}
+
+Toggle buttons are used to display the selected configuration (e.g. programming language, OS, IDE).
+
+To use the buttons in documentation, _add_toggle_ and _end_toggle_ commands are used.
+
+The command _add_toggle_ can be
+- general: _add_toggle{Button Name}_
+- for C++: _add_toggle_cpp_
+- for Java: _add_toggle_java_
+- for Python: _add_toggle_python_
+
+Example:
+@verbatim
+@add_toggle{Button Name}
+
+  text / code / doxygen commands
+
+@end_toggle
+@endverbatim
+
+For example using toggle buttons with text and [code](@ref tutorial_documentation_commands_include) snippets:
+
+@verbatim
+
+### Buttons Example
+
+@add_toggle_cpp
+
+   Text for C++ button
+   @snippet samples/cpp/tutorial_code/introduction/documentation/documentation.cpp hello_world
+
+@end_toggle
+
+@add_toggle_java
+
+   Text for Java button
+   @snippet samples/java/tutorial_code/introduction/documentation/Documentation.java  hello_world
+
+@end_toggle
+
+@add_toggle_python
+
+   Text for Python button
+   @snippet samples/python/tutorial_code/introduction/documentation/documentation.py hello_world
+
+@end_toggle
+
+@endverbatim
+
+Result looks like this:
+
+### Buttons Example
+
+@add_toggle_cpp
+
+   Text for C++ button
+   @snippet samples/cpp/tutorial_code/introduction/documentation/documentation.cpp hello_world
+
+@end_toggle
+
+@add_toggle_java
+
+   Text for Java button
+   @snippet samples/java/tutorial_code/introduction/documentation/Documentation.java  hello_world
+
+@end_toggle
+
+@add_toggle_python
+
+   Text for Python button
+   @snippet samples/python/tutorial_code/introduction/documentation/documentation.py hello_world
+
+@end_toggle
+
+As you can see, the buttons are added automatically under the previous heading.
+
 ### Grouping commands {#tutorial_documentation_commands_group}
 
 All code entities should be put into named groups representing OpenCV modules and their internal
@@ -536,6 +613,8 @@ Write the tutorial {#tutorial_documentation_steps_tutorial}
 
     If you want to insert code blocks from this file into your tutorial, mark them with special doxygen comments (see [here](@ref tutorial_documentation_commands_include)).
 
+    If you want to write the tutorial in more than one programming language, use the toggle buttons for alternative comments and code (see [here](@ref tutorial_documentation_toggle_buttons_commands_include)).
+
 3.  Collect results  of the application work. It can be "before/after" images or some numbers
     representing performance or even a video.
 
@@ -552,22 +631,21 @@ Write the tutorial {#tutorial_documentation_steps_tutorial}
 
 5.  Modify your new page:
     -   Add page title and identifier, usually prefixed with <em>"tutorial_"</em> (see [here](@ref tutorial_documentation_md_page)).
+        You can add a link to the previous and next tutorial using the identifier
+        @verbatim
+@prev_tutorial{identifier}
+@next_tutorial{identifier}
+        @endverbatim
+        @warning Do **not** write the **hashtag (#)**, example: \n Incorrect: @verbatim @prev_tutorial{#tutorial_documentation} @endverbatim Correct: @verbatim @prev_tutorial{tutorial_documentation} @endverbatim
     -   Add brief description of your idea and tutorial goals.
     -   Describe your program and/or its interesting pieces.
     -   Describe your results, insert previously added images or other results.
 
-        To add a video use _htmlonly_, _endhtmlonly_ commands with raw html block inside:
+        To add a youtube video, e.g. www.youtube.com/watch?v= **ViPN810E0SU**, use _youtube_{**Video ID**}:
         @verbatim
-@htmlonly
-<div align="center">
-<iframe
-    title="my title" width="560" height="349"
-    src="http://www.youtube.com/embed/ViPN810E0SU?rel=0&loop=1"
-    frameborder="0" allowfullscreen align="middle">
-</iframe>
-</div>
-@endhtmlonly
+@youtube{ViPN810E0SU}
         @endverbatim
+
     -   Add bibliographic references if any (see [here](@ref tutorial_documentation_commands_cite)).
 
 6.  Add newly created tutorial to the corresponding table of contents. Just find
@@ -576,6 +654,8 @@ Write the tutorial {#tutorial_documentation_steps_tutorial}
     @verbatim
 -   @subpage tutorial_windows_visual_studio_image_watch
 
+    _Languages:_ C++, Java, Python
+
     _Compatibility:_ \>= OpenCV 2.4
 
     _Author:_ Wolf Kienzle