Log Message:
Update xfce4-session to 4.13.0

4.13.0
======
- xfsm has been ported to Gtk3.
- xfsm now does session management for clients using the Gtk application
  dbus interface.
- xfsm has been ported to GDBus.
- Add a switch user button to the logout dialog (Bug #10345)
- UPower dependency has been removed as the suspend/hibernate dbus calls
  were dropped from it.
- Handle screensaver with it's own object (Bug #12603)
- Fix a crash when warning about the screenlocker (Bug #12603)
- When locking fallback to xflock4 first (Bug #12603)
- Add switch-user to the xfsm-logout program
- Translation updates: am, ast, ca, da, de, el, en_AU, es, fi, fr, gl, he,
  hr, hu, id, is, it, ja, kk, ko, lt, ms, nb, nl, nn, oc, pl, pt, pt_BR,
  ru, sk, sr, sv, th, tr, uk, zh_CN,  zh_TW