That's a good point, I suppose globs really do want to import `num::bigint::*`, not `num::*`. Then again, globs are feature-gated...

One part about `pub mod foo;` is that the reexport doesn't have its documentation inlined at the reexport site, but rather it's a redirect. That's not necessarily a downside, but it is something to consider.

Let's go with this for now, and see how it turns out.