"Stay logged in" feature

[malnvenshorn]

I would like to be able to stay logged in. From #918 and #563 I know that I can prolong the session by modifying session.gc_maxlifetime and session.cookie_lifetime in the PHP config, but I don't think this is the preferable way. I would suggest to add a persistent cookie to identify the user and auto log him in when he revisits the site.

[jtojnar]

I think I would prefer to stop using session cookies altogether, and instead store session tokens inside a localStorage of the web app. That will be more consistent and also tie in with #1045

[malnvenshorn]

From a security point of view I wouldn't recommend storing tokens inside the localstorage. Every javascript code running under the same domain can access that.

The ticket you mentioned is about read-only permission if I understand it correctly. I don't see how this is related to the use of localstorage.