Try to skip meta refresh directives.
Replace with a note that a refresh has been skipped,
and a link to the content URL so the user can choose
to visit it or not.
On meta refresh, try to fetch the page
being redirected to (set it as the single-page link).
Make tag_skippable_section skip everything until the matching close tag.
Skip <head> sections (because if we ever see one, it's a parsing error)
and <body> opening tags (because they tend to contain things like color
settings, and also because seeing them is an error.)