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/header.html

@@ -54,4 +54,34 @@ $extrastylesheet
 </table>
 </div>
 <!--END TITLEAREA-->
+<script type="text/javascript">
+//<![CDATA[
+function getLabelName(innerHTML) {
+    var str = innerHTML.toLowerCase();
+    // Replace all '+' with 'p'
+    str = str.split('+').join('p');
+    // Replace all ' ' with '_'
+    str = str.split(' ').join('_');
+    // Replace all '#' with 'sharp'
+    str = str.split('#').join('sharp');
+    // Replace other special characters with 'ascii' + code
+    for (var i = 0; i < str.length; i++) {
+        var charCode = str.charCodeAt(i);
+        if (!(charCode == 95 || (charCode > 96 && charCode < 123) || (charCode > 47 && charCode < 58)))
+            str = str.substr(0, i) + 'ascii' + charCode + str.substr(i + 1);
+    }
+    return str;
+}
+function addToggle() {
+    var $getDiv = $('div.newInnerHTML').last();
+    var buttonName = $getDiv.html();
+    var label = getLabelName(buttonName.trim());
+    $getDiv.attr("title", label);
+    $getDiv.hide();
+    $getDiv = $getDiv.next();
+    $getDiv.attr("class", "toggleable_div label_" + label);
+    $getDiv.hide();
+}
+//]]>
+</script>
 <!-- end header part -->