Add torture-test for new normalization functions.
One problem that this test demonstrates is that word has a tendency to
turn off formatting at a space, and then turn it back on after. I'm not
sure yet whether this is something we should fix.
This is just a wrapper around Pandoc that doesn't normalize with
`toString`. We want to make sure that our own normalization process
works. If, in the future, we are able to hook into the builder's
normalization, this will be removed.
