explaining what's going on. Fixes favorite button jumping left and right
depending on post visibility

The locale can now be configured in settings and is stored in
Vuex. The changes are applied immidiately after selection. The list of
languages is taken from the messages file, which contains all the
available locales (and a new value, `interfaceLanguage`, to control
the translation of this option in the options menu)

Closes #36

Add option to config.json, disabled by default.

localization strings.

Shuffled settings a bit b/c all the settings are in "Attachments" section
depsite the fact not all of them are attachments-related.

Co-authored-by: goofy