Added four scripting languages

I created a section for libraries that allow you to embed other languages into your code and added golua, go-python, otto and v8-go as active/stable examples of such projects.

There also is mattn/go-v8 but chose the one from idada because of the higher amount of activity and contributors.

I also looked through the corresponding section in the go-wiki but most of the other projects are stale since a couple of years.