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/footer.html

@@ -17,5 +17,74 @@ $generatedby &#160;<a href="http://www.doxygen.org/index.html">
 </a> $doxygenversion
 </small></address>
 <!--END !GENERATE_TREEVIEW-->
+<script type="text/javascript">
+//<![CDATA[
+function addButton(label, buttonName) {
+    var b = document.createElement("BUTTON");
+    b.innerHTML = buttonName;
+    b.setAttribute('class', 'toggleable_button label_' + label);
+    b.onclick = function() {
+        $('.toggleable_button').css({
+            border: '2px outset',
+            'border-radius': '4px'
+        });
+        $('.toggleable_button.label_' + label).css({
+            border: '2px inset',
+            'border-radius': '4px'
+        });
+        $('.toggleable_div').css('display', 'none');
+        $('.toggleable_div.label_' + label).css('display', 'block');
+    };
+    b.style.border = '2px outset';
+    b.style.borderRadius = '4px';
+    b.style.margin = '2px';
+    return b;
+}
+function buttonsToAdd($elements, $heading, $type) {
+    if ($elements.length === 0) {
+        $elements = $("" + $type + ":contains(" + $heading.html() + ")").parent().prev("div.newInnerHTML");
+    }
+    var arr = jQuery.makeArray($elements);
+    var seen = {};
+    arr.forEach(function(e) {
+        var txt = e.innerHTML;
+        if (!seen[txt]) {
+            $button = addButton(e.title, txt);
+            if (Object.keys(seen).length == 0) {
+                var linebreak1 = document.createElement("br");
+                var linebreak2 = document.createElement("br");
+                ($heading).append(linebreak1);
+                ($heading).append(linebreak2);
+            }
+            ($heading).append($button);
+            seen[txt] = true;
+        }
+    });
+    return;
+}
+$("h2").each(function() {
+    $heading = $(this);
+    $smallerHeadings = $(this).nextUntil("h2").filter("h3").add($(this).nextUntil("h2").find("h3"));
+    if ($smallerHeadings.length) {
+        $smallerHeadings.each(function() {
+            var $elements = $(this).nextUntil("h3").filter("div.newInnerHTML");
+            buttonsToAdd($elements, $(this), "h3");
+        });
+    } else {
+        var $elements = $(this).nextUntil("h2").filter("div.newInnerHTML");
+        buttonsToAdd($elements, $heading, "h2");
+    }
+});
+$(".toggleable_button").first().click();
+var $clickDefault = $('.toggleable_button.label_python').first();
+if ($clickDefault.length) {
+    $clickDefault.click();
+}
+$clickDefault = $('.toggleable_button.label_cpp').first();
+if ($clickDefault.length) {
+    $clickDefault.click();
+}
+//]]>
+</script>
 </body>
 </html>