[luatex] LuaTeXtra code review

[Karl Berry]

    Seems logical, but it seems also logical that all primitive 

Well, not primitives :).

    start by \lua... I must admit I also prefer
    \newluaattribute... Karl, what do you think?

If it were me, I would consistently start every public macro defined by
a package with a given prefix, \lua in this case.

However, I'm not doing the work, and I won't complain if you go with
with \newlua...  I am well aware that is the convention for everything
else.