Make index inclusion tests from `dashing` output

[michaelblyons]

I notice that the dashing output can probably be parsed to add more tests. Maybe we should make a simple script to do that and add more tests?

Reading docs/vintage.html
docs/vintage.html looks like HTML
Match: 'Enabling Vintage' is type Section at docs/vintage.html#autolink-1666
Match: 'What’s Included' is type Section at docs/vintage.html#autolink-1667
Match: 'What’s Not' is type Section at docs/vintage.html#autolink-1668
Match: 'Under the Hood' is type Section at docs/vintage.html#autolink-1669
Match: 'Mac' is type Section at docs/vintage.html#autolink-1670
Match: 'Ctrl Keys' is type Section at docs/vintage.html#autolink-1671
Match: 'Ex Mode' is type Section at docs/vintage.html#autolink-1672
Match: 'Vintage Mode' is type Guide at docs/vintage.html#autolink-1673

=>

        contains = [
            ('Section', 'Enabling Vintage'),
            ('Section', 'What’s Included'),
            ('Section', 'What’s Not'),
            ('Section', 'Under the Hood'),
            ('Section', 'Mac'),
            ('Section', 'Ctrl Keys'),
            ('Section', 'Ex Mode'),
            ('Guide', 'Vintage Mode'),
        ]
        self._test_a_doc_page_index('docs/vintage.html', contains)

[michaelblyons]

Closing in favor of #52