Add basic AppData support
Fix typo in AppData id
Fix two more typos in AppData
Add default screenshot for AppData
I18n: Update translation bg (100%).

201 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
I18n: Update translation fr (100%).

201 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
Merge branch 'appdata'
Merge branch 'master' of ssh://git.xfce.org/xfce/xfce4-power-manager
Spring cleaning of old and unused icons
Fix make distcheck
Fix conditional check for network manager
I18n: Update translation bg (100%).

201 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
I18n: Update translation nl (100%).

201 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
I18n: Update translation zh_TW (100%).

206 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
I18n: Update translation es (100%).

206 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
I18n: Update translation th (100%).

206 translated messages.

Transifex (https://www.transifex.com/projects/p/xfce/).
Fix an untranslatable string in battery-indicator-plugin
Remove unused variable