This does what it should do (which is a feature that shouldn't require an extension!). I need it to remain logged in on a forum that has become incapable to remember me.
Sadly I can only give it 2 starts because it will reload the page even if I'm in the middle of typing a (long) reply. I don't know if and how it could detect an input form with unsaved changes but it should, ideally!

Alternatively, it could offer to open all links from an auto-reloading page in a new page, that could work too.