MainWorkflow: Make trigger public

Since its undostack is already exposed, there is no need it to be private.

src/Workflow/MainWorkflow.h

@@ -156,14 +156,14 @@ class   MainWorkflow : public QObject
 
         bool                    canRender();
 
+        void                    trigger( Commands::Generic* command );
+
         AbstractRenderer*       renderer();
 
         Commands::AbstractUndoStack*       undoStack();
 
     private:
 
-        void                    trigger( Commands::Generic* command );
-
         void                    preSave();
         void                    postLoad();