Move related files menu item to coverage and turn it unto a submenu instead

package.json

@@ -108,7 +108,7 @@
         "c9.ide.save": "#4a4a60a004",
         "c9.ide.scm": "#d92bb9aeb5",
         "c9.ide.terminal.monitor": "#b76f1c9f24",
-        "c9.ide.test": "#d939644163",
+        "c9.ide.test": "#ba0ed6e586",
         "c9.ide.test.mocha": "#f6cc482886",
         "c9.ide.theme.flat": "#2de8414db7",
         "c9.ide.threewaymerge": "#229382aa0b",

plugins/c9.ide.ui/menus.js

@@ -942,6 +942,10 @@ define(function(require, exports, module) {
                 return item;
             }
             
+            function remove(item){
+                aml.removeChild(item.aml);
+            }
+            
             function show(x, y) {
                 lastCoords = { x : x, y : y };
                 aml.display(x, y);
@@ -1118,6 +1122,12 @@ define(function(require, exports, module) {
                  */
                 append: append,
                 
+                /**
+                 * Remove a menu item from this menu
+                 * @param {MenuItem} item  The item to remove from this menu.
+                 */
+                remove: remove,
+                
                 /**
                  * Show the menu at the specified position
                  * @param {Number} x  The x coordinate specified in pixels from the left of the browser window.