4.15.1

- Add keywords to .desktop files in xfdesktop
- Add 24px and 32px icons
- Remove extra separator from context menu
- Move 'Open in New Window' of root window context menu (#59)
- Remove "Properties..." entry from desktop context menu (#59)
- Translation Updates:
  Albanian, Amharic, Arabic, Armenian (Armenia), Basque, Belarusian,
  Belarusian (Tarask), Bulgarian, Catalan, Chinese (China), Chinese
  (Hong Kong), Chinese (Taiwan), Croatian, Czech, Danish, Dutch,
  Eastern Armenian, English (Australia), English (Canada), English
  (United Kingdom), Estonian, Finnish, French, Galician, Georgian,
  German, Greek, Hebrew, Hungarian, Icelandic, Indonesian, Interlingue,
  Italian, Japanese, Kazakh, Korean, Lithuanian, Malay, Norwegian
  Bokmål, Norwegian Nynorsk, Occitan (post 1500), Persian (Iran),
  Polish, Portuguese, Portuguese (Brazil), Romanian, Russian, Serbian,
  Slovak, Slovenian, Spanish, Swedish, Thai, Turkish, Ukrainian,
  Uyghur, Uzbek