Localized user-guide screenshots

Created by: el00ruobuob

I did notice in #735 (closed) that user-guides did not used their local png folders. So i made this small ruby script to copy localized png files to the site directory during the build.

Working perfectly here.

Then all the localized screenshot i took to solve #729 (closed) could be used, and every user could have a localized experience up to the screenshot itself.

Up to you to test @erciccione

Created by: el00ruobuob

example in verification-windows-beginner.html: example in restore_from_keys.html:

Created by: el00ruobuob

Just changed the code to avoid reading language from config file and instead use the "lang" defines in site.config. This way it is more trivial, and the files are not copied for all languages each time a language is build, but only once for the current language.

Created by: el00ruobuob

Tested successfully on a single browser, as it's just building issue and not rendering issue.

Created by: el00ruobuob

No one wants to have a look at it? @erciccione @MaxXor @mattcode55 ? @rehrar ?