Thus introducing a few functional regressions, but it's going to be
easier to fix things up without the old code knocking around and
getting in the way.
Now there is now longer a dummy DOM element corresponding to the macro
itself. Instead, macros must create a single element child. This allows
us to more easily fit Bootstrap's requirements for HTML layout (eg,
that problem with links in navbars not being recognised). The
refactoring isn't complete, there are still a few bugs to chase down
