Fix a few memory leaks

Some raw pointers never got released.

These errors were found by running QtCreator via Valgrind.

Change-Id: I9c5b2862b98597f3e468d573e7126d7d9ec46b05
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/plugins/coreplugin/designmode.cpp

@@ -189,6 +189,7 @@ void DesignMode::unregisterDesignWidget(QWidget *widget)
     foreach (DesignEditorInfo *info, d->m_editors) {
         if (info->widget == widget) {
             d->m_editors.removeAll(info);
+            delete info;
             break;
         }
     }