Shortcuts: Remember them even for plugins that are not loaded

This also fixes the issue that shortcuts of designer integration gets
lost if it doesn't get initialized.

Task-number: QTCREATORBUG-4264
Task-number: QTCREATORBUG-11399
Change-Id: Ieb4fe5fd345e69aa62403e4578fa6028400aff6f
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/coreplugin/mainwindow.cpp

@@ -147,6 +147,8 @@ MainWindow::MainWindow() :
     m_zoomAction(0),
     m_toggleSideBarButton(new QToolButton)
 {
+    ActionManager::initialize(); // must be done before registering any actions
+
     (void) new DocumentManager(this);
     OutputPaneManager::create();
 
@@ -344,9 +346,6 @@ void MainWindow::extensionsInitialized()
     m_vcsManager->extensionsInitialized();
     m_navigationWidget->setFactories(ExtensionSystem::PluginManager::getObjects<INavigationWidgetFactory>());
 
-    // reading the shortcut settings must be done after all shortcuts have been registered
-    m_actionManager->initialize();
-
     readSettings();
     updateContext();