Working on the @username convention. We can call user even if using only the first...

Working on the @username convention. We can call user even if using only the first part of his username, for example, we can call "Jordan Jambazov" only using @Jordan. The supplied module forum.utils.userlinking deals with the active users (the one that took part in the discussion writing question, comment or answer).

git-svn-id: http://svn.osqa.net/svnroot/osqa/trunk@650 0cfe37f9-358a-4d5e-be75-b63607b5c754