[Feature] Allow signing in to access privileged actions

[Leichesters]

While I like the idea of accessing StackOverflow anonymously, there are some things I do miss. For example, once you reach 1,000 Karma you can see the individual votes of questions and answers https://stackoverflow.com/help/privileges/established-user.

I propose to add a login functionality. Not per instance, but individual users should be able to log in on AnonymousOverflow. Everything should still be accessed without authentication (or fallback to that if anonymous access does not work) and privileged things should be fetched using auth.