[Java] Expose ILuaObject to the API

It's really quite simple. I'd just like dan200.computer.core.ILuaObject to be exposed to the API. Considering that it's an easy way to make Lua objects from Java (you don't accept any LuaJ objects), I'm sure I'm not the only one.
Note that I don't plan on using it without permission, because AFAIK, it's illegal to do so.

Not right now, maybe in the future.