i18n(calendarium): update .pot and .po files with new bg-opacity strings

- Deduplicate .pot entries
- Add 'Background opacity' and its tooltip to all .po files

Author: KAMI911

calendarium@kami911/files/calendarium@kami911/po/calendarium@kami911.pot

@@ -614,14 +614,16 @@ msgstr ""
 msgid "Article of the day"
 msgstr ""
 
-#: desklet.js
-msgid "Wikipedia"
-msgstr ""
-
 #: desklet.js
 msgid "Enable births, deaths, or featured article"
 msgstr ""
 
 #: desklet.js
 msgid "No data available"
 msgstr ""
+
+msgid "Background opacity"
+msgstr ""
+
+msgid "0 = fully transparent (wallpaper shows through), 1 = solid black background"
+msgstr ""