Make editor names consistent.

cms/templates/widgets/problem-edit.html

@@ -16,7 +16,7 @@
                         class="problem-editor-icon dropdown"></span></a></li>
             </ul>
             <ul class="editor-tabs">
-                <li><a href="#" class="xml-tab tab" data-tab="xml">Edit Source XML</a></li>
+                <li><a href="#" class="xml-tab tab" data-tab="xml">Use Advanced Editor</a></li>
                 <li><a href="#" class="cheatsheet-toggle" data-tooltip="Toggle Cheatsheet">?</a></li>
             </ul>
         </div>

common/lib/xmodule/xmodule/js/src/problem/edit.coffee

@@ -59,7 +59,7 @@ class @MarkdownEditingDescriptor extends XModule.Descriptor
   ###
   confirmConversionToXml: ->
     # TODO: use something besides a JavaScript confirm dialog?
-    return confirm("If you convert to the XML source representation, you cannot go back to using markdown.\n\nProceed with conversion to XML?")
+    return confirm("If you convert to the XML source representation, which is used by the Advanced Editor, you cannot go back to using the Simple Editor.\n\nProceed with conversion to XML?")
 
   ###
   Event listener for toolbar buttons (only possible when markdown editor is visible).