Localization

[emanuele45]

Hi, I was looking to use the code in another project, though that one is localized in multiple languages, so I'd need to have also the only string user-facing easily replaceable in languages other than English (there are also two error messages, but they should not appear to the user, worst case to the developer so it's fine for me to leave them in English).

I'm not that good with javascript, so instead of sending a pull request I'm going to attach a patch here.
If you find it usable and worth the hassle feel free to use it. 😉

0001-Extend-code-to-have-localization-of-the-currently-si.patch.txt