Add Basque localisation

[xabirequejo]

Hi,
I believe I have translated all the files and most of the strings for Buran to be usable in Basque.
It would be great if Basque locale was added to Buran in a future update.
Thanks

[Corewala]

Hi, this is really amazing work, thank you so much! I noticed that "show_inline_images" and "pkcs_notice" aren't translated yet, but other than that everything looks good! Since I'm going to work on a couple other bugfixes before the next release, I'll keep this PR open for now, but I'll definitely merge it before v1.13!

[Corewala]

Because of df6c159 you don't need to translate "load_image" since it isn't used anywhere.

[xabirequejo]

Truth is I have no idea how to translate pkcs_notice so I thought leaving it as is was the better option.
I'll edit the file to include inline_images and remove load_image.

Could PKCS12 client keystores be translated as ≈ password wallets or managers?

[Corewala]

Could PKCS12 client keystores be translated as ≈ password wallets or managers?

Honestly I was considering changing the wording for that string since elsewhere they're called "client certificates." Would "Only PKCS12 certificate files are currently supported" be easier to translate?

[xabirequejo]

Yes, that would make it a lot easier. So long as it's still accurate.
≈ PKCS12 ziurtagiri-fitxategiak soilik erabil daitezke oraingoz.

[Corewala]

Yes, that should be accurate, and honestly probably more informative than "client keystores."