Improve Lua Engine Documentation

I've been going through and slowly adding documentation for the default Lua engine, as it is sorely lacking at the moment. Documentation generation files are stored under /documentation. It's currently being generated with LDoc, and i'm not including it, so you'll need that in order to generate the documentation. More info is in the /documentation folder.

Although I've only gotten around to a handful of files so far, i have at least touched into every file to make sure it's included into the documentation (even if nothing shows up).