Allow configuration of html5ever::driver::ParseOpts

[ticky]

Currently, it doesn’t appear to be possible to configure how html5ever’s parser is configured.

This is mostly okay but if you want to override scripting_enabled or other such settings you can’t right now!

[causal-agent]

I'm not sure if Html::parse_document and parse_fragment should take ParseOpts. How many calls would pass something other than Default::default()? Without it, I think you could call the html5ever parser directly:

let parser = html5ever::driver::parse_document(scraper::Html::new_document(), parse_opts);
let doc = parser.one(html_string);

[ticky]

Confirmed that this does definitely work! 😄

I didn’t even consider that you could work “backwards” like that by giving html5ever a scraper document as the sink. Maybe a better approach than allowing this from scraper methods then would be to note this as an option?