Possibility to add/define new languages with arbitrary names

[blablubbabc]

Summary

This request may initially sound similar to #86, but is instead asking for the possibility to add new arbitrary (even made-up) languages.

Uses cases:

• Add different, even made-up variations of the same language, like for example English, Pirate. Currently, it is only possible to select from a predefined list of language variants, like for example English, United Kingdom [en-GB] or English, United States [en-US]. And it is not possible to select the same language variant twice but then given one of them a new custom language code (i.e. it is not possible to add English, United Kingdom [en-GB] twice and change the language code of one of them to en-pirate or something like that).
• Add new languages, even ones that are made up like for example Klingon, etc.

Those languages would be saved with custom non-standard language codes. And they would obviously not support machine translations.

It may be possible to select some not yet used language (that is know to not be used in the future either) from the predefined list and then change the language code to something custom. But this does not seem to be ideal.

[svasilenkov]

@blablubbabc Thank you for the suggestions, we have added them to our to-do list.