Strip links fully and reformat the doc.

This ensures that we don't fail tests after changing interface versions
due to missing documentation on developer's system.
Temporarily hide cross package testing

We need to hide this for now as it will fail every time we change the
interface version. A solution would be to bundle a package with Haddock
test suite and install + generate docs for it every time we run tests
and then remove it straight afterwards. I'm hiding this until I think of
a semi-clean way to do this.