[FIX] web_editor, website: allow to detect indirect clones

When cloning a snippet section thanks to the editor, the associated
snippet options' `on_clone` methods are called. Now these methods
receive a new argument `options`. The option this commit introduces
is the `isCurrent` one. It allows the method to know if the snippet
section it is associated to is the one that was cloned or if it is a
child of the one that was cloned.

This is useful to solve a known bug when cloning elements which have
bootstrap columns:

- When one column is cloned we want it to lose its col-*-offset-*
  classes so that the offset is not duplicated (only the column).

- When a container with column children is cloned we do not want
  these column' offsets to be removed (we want the whole cloned
  container to be the same).

addons/web_editor/static/src/js/snippets.editor.js

@@ -1010,7 +1010,9 @@ data.Editor = Class.extend({
         this.$target.after($clone);
         this.buildingBlock.call_for_all_snippets($clone, function (editor, $snippet) {
             for (var i in editor.styles) {
-                editor.styles[i].on_clone($snippet);
+                editor.styles[i].on_clone($snippet, {
+                    isCurrent: ($snippet.is($clone)),
+                });
             }
         });
         return false;

addons/website/static/src/js/website.snippets.editor.js

@@ -265,9 +265,13 @@ options.registry["margin-x"] = options.registry.marginAndResize.extend({
 
         return this.grid;
     },
-    on_clone: function ($clone) {
-        var _class = $clone.attr("class").replace(/\s*(col-lg-offset-|col-md-offset-)([0-9-]+)/g, '');
-        $clone.attr("class", _class);
+    on_clone: function ($clone, options) {
+        // Below condition is added to remove offset of target element only
+        // and not its children to avoid design alteration of a container / block.
+        if (options.isCurrent) {
+            var _class = $clone.attr("class").replace(/\s*(col-lg-offset-|col-md-offset-)([0-9-]+)/g, '');
+            $clone.attr("class", _class);
+        }
         return false;
     },
     on_resize: function (compass, beginClass, current) {