Automatic translation of localisation strings

It would be cool if we could specify a pair within the metadata JSON for a `*.json` strings file and use `localization-tools.py` to automatically fill in missing localizations. We would have to mark them within the text, perhaps `%%MACHINE_TRANSLATED_arg-spa%%` or something and then strip that out in the website. It would also be nice if the script reported what progress it made and even more amazing if it crawled the entire graph and translated as much as it could with some flag/option.