Publicly expose VisualizationFrame::addPanelByName() (#1303)

... to allow saving of programmatically created panels.
Otherwise, panels can only be added via addPane(), which doesn't add them to `custom_panels_`
and thus doesn't save their settings.

src/rviz/visualization_frame.h

@@ -110,6 +110,11 @@ Q_OBJECT
                                 Qt::DockWidgetArea area = Qt::LeftDockWidgetArea,
                                 bool floating = true );
 
+  QDockWidget* addPanelByName( const QString& name,
+                               const QString& class_lookup_name,
+                               Qt::DockWidgetArea area = Qt::LeftDockWidgetArea,
+                               bool floating = true );
+
   /** @brief Load the "general" config file, which has just the few
    * things which should not be saved with a display config.
    *
@@ -272,11 +277,6 @@ protected Q_SLOTS:
   void markRecentConfig(const std::string& path);
   void updateRecentConfigMenu();
 
-  QDockWidget* addPanelByName( const QString& name,
-                               const QString& class_lookup_name,
-                               Qt::DockWidgetArea area = Qt::LeftDockWidgetArea,
-                               bool floating = true );
-
   /** @brief Loads custom panels from the given config node. */
   void loadPanels( const Config& config );