Match headings on trimmed strings to avoid whitespace causing mismatches (Fixes #452)

[gijsk]

@msujaws this should be fairly easy to review. The HTML changes are just because generate-testcase.js changes some formatting to how the HTML used to be.

The reason we have all this code is to deal with cases where the title is something like "New York Times - Some title", so we remove the generic website name stuff. This code then looks to see if the prefix might actually just be a legit part of the title by checking headings inside the page for the same title. As noted in #452 this fixes the engadget title, but as you can see here it also improves the telegraph testcase, so it seems plausible it'll affect a good number of articles.