Lang file inheritance for accessibility and translation

Implement a system where lang files can inherit strings from a parent language, improving translation efficiency and accessibility.

The proposal is to support default translations for more than just English. Since many languages are actually dialects or variations of the same or similar language, in many cases it makes more sense to have them “inherit” translations from a main language that is not English, while allowing for the differences to override the defaults.

For translation, this means dialects can translate only the differences in language, saving immense time on translation and focusing on the important stuff; it means that new dialects with a high translation coverage are less likely to just be the percent of overlap between them.

For accessibility, this means players who speak multiple, non english languages can have custom translation with set parent languages.

For mapmakers, this means supporting so many more languages with relative ease, reducing redundancy, and allowing for ease of updates later down the line; for example pluralizing a string, you may only have to change it in 1 Spanish instead of all 8, or 1 German instead of 6, etc.

This also means that mapmakers can override default strings for all languages in one fell swoop by changing an en_us translation.

Old:

RP lang  -> Official Translation -> en_us -> RP en_us

New:

RP lang -> RP parent -> RP en_us -> Official Translation -> Official Parent -> en_us