* Add ability to mark dmails as unread.
* Fix users.unread_dmail_count to not count deleted dmails.
* Fix show action so that API calls don't mark dmails as read.
* Don't show the unread dmail notice on the /dmails page itself.
* Stop using users.has_mail flag.
Remove links to the aliases and implications pages from the main menu.
Put them in the submenu on the /tags page instead.
These pages are too rarely used to deserve being in the toplevel menu.
They also weren't easy to find for non-Builders. The toplevel menu
shouldn't be dependent on user level.
* Replace /session/new with /login and /session/sign_out with /logout.
* Rename 'sign in' to 'login'.
This changes are to make urls cleaner and terminology more consistent.
Change wiki page search to redirect to exact matches only when using the
quick search bar. Fixes searches sometimes unexpectedly redirecting when
doing a regular (non-quick) search that happens to return a single result.
Also remove the logic that tries to expand the search when no results
are found. This will eventually be replaced with a smarter "did you mean?"
search.
