Switch to NLua, use Dictionary<> for Part.Init() params

Unity was periodically crashing with UnityLuaInterface, switching to
NLua has seemed to fix it. Also added a method for SimpleJson.GetKeys()
Remove unnecessary lua files

KopiLua is implemented in C#, se we don't need the lua52.dll plugins and
stuff (I think)
Add support for rotation in LoadShip, update test scene