Added duplicate feature for variable.

public/app/features/templating/editorCtrl.js

@@ -96,6 +96,14 @@ function (angular, _) {
       }
     };
 
+    $scope.duplicate = function(variable) {
+      $scope.current = angular.copy(variable);
+      $scope.variables.push($scope.current);
+      $scope.current = $scope.variables[$scope.variables.length - 1];
+      $scope.current.name = 'copy_of_'+variable.name;
+      $scope.updateSubmenuVisibility();
+    };
+
     $scope.update = function() {
       if ($scope.isValid()) {
         $scope.runQuery().then(function() {

public/app/features/templating/partials/editor.html

@@ -59,6 +59,11 @@
 									Edit
 								</a>
 							</td>
+              <td style="width: 1%">
+                <a ng-click="duplicate(variable)" class="btn btn-inverse btn-small">
+                  Duplicate
+                </a>
+              </td>
 							<td style="width: 1%"><i ng-click="_.move(variables,$index,$index-1)" ng-hide="$first" class="pointer fa fa-arrow-up"></i></td>
 							<td style="width: 1%"><i ng-click="_.move(variables,$index,$index+1)" ng-hide="$last" class="pointer fa fa-arrow-down"></i></td>
 							<td style="width: 1%">