Consider adding language internationalization.

This was pointed out in https://www.intfiction.org/forum/viewtopic.php?f=38&t=3937&start=10#p139440


> I know this is a detail, but is it possible to propose in the command line options a translation of the sentence: ```[Hit any key to exit.]``` (for other languages.)
> Code:
> ```
> # Exit_sentence "Hit any key to exit."
> Exit_sentence "Appuyez sur une touche pour quitter."
> ```
