Expand required macros in macroexpand-all

[brandonwillard]

Minor change that allows macroexpand-all to expand required macros.

See this discussion for some context.

[Kodiologist]

1. Spin out the unrelated style edits to walk.hy into their own commit.
2. Put the test macro into one of the existing files in tests/resources instead of its own file.
3. I think the test is too brittle because it depends on require expanding to None. Instead, try something like (assert (= (last (macroexpand-all '(require-macro))) '(setv blah 1))).
4. Update NEWS and AUTHORS.

Otherwise, this looks good.

[brandonwillard]

Ha, yeah, I forgot about those docstring edits; I'll just retract them.

[brandonwillard]

Also, I wasn't sure whether or not it was desirable to have a require expand to None. It doesn't seem to hurt anything, but does produces a rather redundant expression (e.g. an unnecessary (do None ...)).

We could easily filter-out those Nones, but that would introduce topics like expression simplification/normalization, canonical forms, etc., and none of that was going on in the module already.

[Kodiologist]

Right. Don't attempt to remove it for now.

[brandonwillard]

Also, before I forget, that require in walk isn't side effect-free, in that it adds the required macros to the calling module, which seems less than ideal.

I considered creating a temporary shallow copy of the calling module (or at least the hy.macros._hy_macros dicts) for a side-effect free version, but didn't because it appeared to relate to @gilch's comments on namespace enhancements and possibly other fundamental changes that would facilitate such an implementation.

[Kodiologist]

Welcome to the Hyve!

[brandonwillard]

Thanks; I look forward to helping everyone get Hy! (My apologies, in advance)