>>/5630/
> I don't want to copy every outside url manually to open them.

The latest Tor browser update is for you:
> Tor Browser 6.5 -- January 24 2017

>  * Bug 17334: Spoof referrer when leaving a .onion domain

Allowing referrers on per-site basis is a bit harder to do. You still need to use about:config and manually set it, post somewhere and set it back when you are done.

 >>/5631/
> Yes, that's an antispam measure, so it has benefits.

Well, it worth just as much as relying on the browser's user-agent for anti-spam. Nothing. Even the most simple spambots include referrer spoofing. And when referrers are used for "security purpose" (like at Webfaction), I become so confused: I don't know whether I should cry or laugh.