Going to need a way to pass arguments into the XS function anyway, so
might as well do the entire arg parsing step in XS while we're at it.
Provides a significant speedup for tiny inputs as well, but I don't find
that too interesting.
It works and can format all "plain" Perl data, but has a few known bugs
and limitations that still need to be worked out.
It's about 8x smaller than JSON::XS's encoder and *much* smaller than
Cpanel::JSON::XS, but this is just a first attempt, it'll grow.