refactor(lua): use less opaque trick
refactor(lua): use less opaque trick

As noted here:

    https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html

we have new options now:

> C++20 introduces the __VA_OPT__ function macro. This macro may only
> appear in the definition of a variadic macro. If the variable argument
> has any tokens, then a __VA_OPT__ invocation expands to its argument;
> but if the variable argument does not have any tokens, the __VA_OPT__
> expands to nothing:
>
>     #define eprintf(format, ...) \
>         fprintf (stderr, format __VA_OPT__(,) __VA_ARGS__)
>
> __VA_OPT__ is also available in GNU C and GNU C++.
>
> Historically, GNU CPP has also had another extension to handle the
> trailing comma: the ‘##’ token paste operator has a special
> meaning when placed between a comma and a variable argument. Despite
> the introduction of __VA_OPT__, this extension remains supported in
> GNU CPP, for backward compatibility. If you write
>
>     #define eprintf(format, ...) fprintf (stderr, format, ##__VA_ARGS__)
>
> and the variable argument is left out when the eprintf macro is used,
> then the comma before the ‘##’ will be deleted. This does not
> happen if you pass an empty argument, nor does it happen if the token
> preceding ‘##’ is anything other than a comma.

Clang supports all this stuff too. Switching to __VA_OPT__ seems
clearer, so there we go.

wincent/command-t,wincent/command-t,wincent/command-t