country-level i18n support

[jlsjonas]

This is a feature request.

Prerequisites

yes

Description

The same language can wildly differ between countries, f.e. Dutch in the Netherlands & Dutch in Belgium, while having similarities, have significant differences too.
The same counts for French, German, ...

To account for this I'd suggest displaying the language name in the dropdown, besides just the flag; I believe the backend should already support nl_BE-style language names so that shouldn't be an issue.

[aocneanu]

Sounds like a good direction but I'm not aware of all the current implications.

[jlsjonas]

I'll be doing initial implementations soon (+-2weeks, I hope), as we'll need it.
Will list potential issues & provide prs where possible