Autolink improvements

[lol768]

From what I understand,

• Autolink assumes only domains with a leading www. should be linked. Many domains are configured to redirect to the "bare" variant without the www since it is technically unnecessary, so this assumption does not hold.
• Autolink assumes the insecure http:// protocol. This opens the visitor up to a MitM if they've not visited the site before (for no HSTS preload) or the site doesn't use HSTS ^{and no redirect is cached}.

It is proposed:

• This feature use the Public Suffix List to detect references to domains.
• The default protocol be changed to https:// since the vast majority of browser page loads are performed using HTTPS nowadays (https://letsencrypt.org/stats/#percent-pageloads). If the user needs to refer to a legacy site, they can specify the link explicitly.