4.15.2

- Introduced 'XfceGtkActionEntry' as replacement for the deprecated
  'GtkAction', 'GtkActionEntry' in order to keep simple menu creation.
  This includes various support methods, like:
  'xfce_gtk_translate_action_entries' to to translate a list of
     XfceGtkActionEntrys
  'xfce_gtk_accel_group_append' to register the provided accelerators of
     the entries
  'xfce_gtk_get_action_entry_by_id' to find a single XfceGtkActionEntry,
     e.g. by using a enumeration
  'xfce_gtk_***_new_from_action_entry' to create the specific menu- or
     tool-items from an XfceGtkActionEntry
- Add a widget for filename input (Bug #16542)
- Enabled doc generation for XfceGtkActionEntry and related methods
- Enabled doc generation for new widget 'xfce-filename-input'
- Switch Ctrl+Alt+Del to xfce4-session-logout (Bug #11979)
- Add more default keyboard shortcuts (Bug #16470)
- shortcuts: Replace xfrun4 by xfce4-appfinder
- shortcuts: Also map Homepage to browser
- shortcuts: Remove calculator shortcut
- Update gitignore
- Translation Updates:
  Albanian, Basque, Belarusian, Chinese (China), Chinese (Taiwan),
  Croatian, Danish, Dutch, French, Galician, German, Hebrew, Hungarian,
  Kazakh, Malay, Norwegian Bokmål, Portuguese, Portuguese (Brazil),
  Russian, Serbian, Slovenian, Swedish, Ukrainian