Move xfce' special settings to xdg-Lubuntu, which is read before the session start (which seems to be needed)

debian/changelog

@@ -1,7 +1,7 @@
 lubuntu-default-settings (0.44) UNRELEASED; urgency=medium
 
   [ Julien Lavergne ]
-  * src/etc/xdg/lubuntu/xfce4/xfconf/xfce-perchannel-xml
+  * src/etc/xdg/xdg-Lubuntu/xfce4/xfconf/xfce-perchannel-xml
    - Add xfce4-power-manager.xml to enable the tray icon of xfce4-power-manager
      by default.
   * debian/lubuntu-default-settings.install

debian/lubuntu-default-settings.install

@@ -5,10 +5,10 @@ etc/xdg/lubuntu/lxdm/
 etc/xdg/lubuntu/lxterminal/
 etc/xdg/lubuntu/menus/lxde-applications.menu
 etc/xdg/lubuntu/menus/lxgames-applications.menu
-etc/xdg/lubuntu/xfce4/
 etc/xdg/lxqt/
 etc/xdg/lxsession/Lubuntu/
 etc/xdg/lxsession/Lubuntu-Netbook/
+etc/xdg/xdg-Lubuntu/xfce4/
 etc/xdg/pcmanfm/
 usr/bin/
 usr/share/applications/lubuntu-screenlock.desktop