Multi-language localization support for single reverence instance

[DarkFenX]

Initially, i wanted to reimplement localization engine in Phobos to have this feature, however i think proper place for it is in reverence.

What i want cfg._localization to be able to do (not going to change anything above it):

• Provide list of available languages
• Be able to fetch message for specified messageID and language

I think this should be rather easy to implement and keep 100% compatibility with current API (use language passed to reverence instance as default, fall back to this default if no language was specified when getting message). If you're fine with it, i can implement it and make a pull request.