[gtkmm] Gtk::ModelButton: Fix property_icon(), add property_use_markup()

[Kjell Ahlstedt <kjellahl src gnome org>]

commit b9da9d643b6f1afc2807cc48f3161404bde0c4d1
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Fri Jan 18 10:49:58 2019 +0100

    Gtk::ModelButton: Fix property_icon(), add property_use_markup()
    
    Gio::Icon is refcounted. It shall be stored in a Glib::RefPtr.

 gtk/src/modelbutton.hg | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/gtk/src/modelbutton.hg b/gtk/src/modelbutton.hg
index e6a2a879..d75b44e0 100644
--- a/gtk/src/modelbutton.hg
+++ b/gtk/src/modelbutton.hg
@@ -64,8 +64,9 @@ public:
   _CTOR_DEFAULT
 
   _WRAP_PROPERTY("role", ButtonRole)
-  _WRAP_PROPERTY("icon", Gio::Icon)
+  _WRAP_PROPERTY("icon", Glib::RefPtr<Gio::Icon>)
   _WRAP_PROPERTY("text", Glib::ustring)
+  _WRAP_PROPERTY("use-markup", bool, newin "3,96")
   _WRAP_PROPERTY("active", bool)
   _WRAP_PROPERTY("menu-name", Glib::ustring)
   _WRAP_PROPERTY("inverted", bool)