Translation of the translators' languages in the credits

[Itms]

There is a loophole in the process of choosing which languages will be included in a released version of the game: when a new language is included (for instance Bulgarian in A20), usually we wait for translation freeze, add it in remove-incomplete-translations.sh and we're done.

Now if we do that and add the new language in creditTranslators.py​ and run the script, that will modify the credit strings and break the string freeze (the name of the new language will have to be translated).

I think there is no way to fix that (the only way is to predict which languages will be 90% complete when we freeze the strings, which is dangerous).

We could decide not to translate the language name: then we have the possibility to put the language name in English, or in the language itself ("Français" for French, "Deutsch" for German, etc.) or both ("Español - Spanish").

This is blocking the string freeze currently.

[Itms]

In 17904:

Change the language names for translation credits to the names in the original language.
This removes the loophole in our release process, fixes #3827.