ANN: New Top Nav Bar now live!

[williamstein]

@haraldschilly just spent the last week totally rewriting and cleaning up the code of the top navbar. It's now live. It's easy to get used to, since it's almost the same as before, except that the icons/buttons now all line up properly, and there is a new notifications tab (the mailbox), with improved functionality, letting you keep track of whenever you are @mentioned.

Also, this new top navbar works much better on mobile phones!