add dropdown menu for backward and forward items
Submitted by Christian Hergert
Currently when you click the "back" or "forward" buttons above the editor, it is not clear where they will go. We should add the ability to show a dropdown menu upon right click of the buttons.
The items can be retrieved from the IdeNavigationList. We might need to add a :title property to IdeNavigationListItem. We should create a GMenu from the navigation list, and then create a GtkMenu from that with gtk_menu_new_from_model().