ANNOUNCE: libxfce4ui 4.21.0 released

[Gaël Bonithon]

libxfce4ui 4.21.0 is now available for download from
  
  https://archive.xfce.org/src/xfce/libxfce4ui/4.21/libxfce4ui-4.21.0.tar.xz
  https://archive.xfce.org/src/xfce/libxfce4ui/4.21/libxfce4ui-4.21.0.tar.xz?sha1
  https://archive.xfce.org/src/xfce/libxfce4ui/4.21/libxfce4ui-4.21.0.tar.xz?sha256


What is libxfce4ui?
===================

Libxfce4ui is used to share commonly used Xfce widgets among the Xfce
applications.

Website: 
  https://docs.xfce.org/xfce/libxfce4ui/start


Release notes for 4.21.0
========================
[Please note that this is a development release.]

- Expose xfce-cell-renderer-icon
- build: Automate copyright year management
- Add missing symbols to GNU visibility
- Add xfce-tree-view from exo
- Add xfce-open from exo
- Add xfce-desktop-item-edit from exo
- Add xfce-icon-chooser-dialog and xfce-icon-view from exo
- build: Remove libxfce4ui-config.h from GI
- build: Add missing check for mmap
- Add xfce-gtk-extensions from exo
- Add xfce-gdk-pixbuf-extensions from exo
- Add xfce-execute from exo
- I18n: Update po/LINGUAS list
- xfce4-about: Add .desktop file to the settings manager
- clipboard-manager: Preserve all image formats when taking ownership
- meson-build: Use SPDX license expression
- meson-build: Update debug/optimization flag management
- Delete obsolete file libxfce4ui-1.pc.in
- build: Use VERSION_FULL intead of VERSION or PACKAGE_VERSION
- autotools-build: Fix EXTRA_DIST redefinition
- Add meson build
- build: Include local header libxfce4ui/libxfce4ui.h
- build: Fix include guard position
- Set up GNU symbol visibility for libxfce4kbd-private
- Migrate to xdt-gen-visibility and xdt-check-abi
- Add variadic functions to Vala
- Fix namespace for GObject introspection
- Translation Updates:
  Albanian, Amharic, Arabic, Armenian, Armenian (Armenia), Asturian,
  Azerbaijani, Basque, Belarusian, Bengali, Bulgarian, Catalan, Chinese
  (China), Chinese (Hong Kong), Chinese (Taiwan), Croatian, Czech,
  Danish, Dutch, Eastern Armenian, English (Australia), English (United
  Kingdom), Estonian, Finnish, French, Galician, Georgian, German,
  Greek, Hebrew, Hungarian, Icelandic, Indonesian, Interlingue,
  Italian, Japanese, Kazakh, Korean, Latvian, Lithuanian, Malay,
  Norwegian Bokmål, Norwegian Nynorsk, Occitan (post 1500), Persian
  (Iran), Polish, Portuguese, Portuguese (Brazil), Romanian, Russian,
  Serbian, Slovak, Slovenian, Spanish, Swedish, Telugu, Thai, Turkish,
  Ukrainian, Urdu, Urdu (Pakistan), Uyghur, Venetian, Welsh