[glade/popover] Add since attributes

[Matthias Clasen <matthiasc src gnome org>]

commit 932e85c66ed3af887919e0f40bb4899f4bacb66a
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Jan 19 13:51:50 2015 -0500

    Add since attributes
    
    GtkPopover was introduced in 3.12, GtkPopoverMenu and GtkModelButton
    are coming in 3.16.

 plugins/gtk+/gtk+.xml.in |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/plugins/gtk+/gtk+.xml.in b/plugins/gtk+/gtk+.xml.in
index 5fb2070..ca35bb0 100644
--- a/plugins/gtk+/gtk+.xml.in
+++ b/plugins/gtk+/gtk+.xml.in
@@ -3243,7 +3243,7 @@
         </packing-properties>
       </glade-widget-class>
       
-      <glade-widget-class name="GtkPopover" generic-name="popover" _title="Popover" toplevel="True">
+      <glade-widget-class name="GtkPopover" generic-name="popover" _title="Popover" toplevel="True" 
since="3.12">
         <constructor-function>glade_gtk_popover_constructor</constructor-function>
         <create-editable-function>glade_gtk_popover_create_editable</create-editable-function>
         <properties>
@@ -3254,7 +3254,7 @@
         </properties>
       </glade-widget-class>
 
-      <glade-widget-class name="GtkPopoverMenu" generic-name="popovermenu" _title="Popover Menu" 
toplevel="True">
+      <glade-widget-class name="GtkPopoverMenu" generic-name="popovermenu" _title="Popover Menu" 
toplevel="True" since="3.16">
         <constructor-function>glade_gtk_popover_menu_constructor</constructor-function>
         <create-editable-function>glade_gtk_popover_menu_create_editable</create-editable-function>
         <post-create-function>glade_gtk_popover_menu_post_create</post-create-function>
@@ -3287,7 +3287,7 @@
         </properties>
       </glade-widget-class>
 
-      <glade-widget-class name="GtkModelButton" generic-name="modelbutton" _title="Model Button">
+      <glade-widget-class name="GtkModelButton" generic-name="modelbutton" _title="Model Button" 
since="3.16">
         <post-create-function>glade_gtk_model_button_post_create</post-create-function>
         <read-widget-function>glade_gtk_model_button_read_widget</read-widget-function>
         <write-widget-function>glade_gtk_model_button_write_widget</write-widget-function>