GtkWidget: Start renaming widget->window

GtkWidget: Start renaming widget->window

This is an automated change doing these command:

git sed -f g gtk_widget_set_has_window gtk_widget_set_has_surface
git sed -f g gtk_widget_get_has_window gtk_widget_get_has_surface
git sed -f g gtk_widget_set_parent_window gtk_widget_set_parent_surface
git sed -f g gtk_widget_get_parent_window gtk_widget_get_parent_surface
git sed -f g gtk_widget_set_window gtk_widget_set_surface
git sed -f g gtk_widget_get_window gtk_widget_get_surface
git sed -f g gtk_widget_register_window gtk_widget_register_surface
git sed -f g gtk_widget_unregister_window gtk_widget_unregister_surface

git checkout NEWS*