Hacked-up culllist: stores user pointers rather than CullItem, as creating them seems...

Hacked-up culllist: stores user pointers rather than CullItem, as creating them seems to be very expensive and wasteful. Doesn't support silent quits (yet), and User::QuitUser seems to trigger *many* times per user before they are removed (socketengine getting write events to closed socket perhaps). It's still much quicker than the old way (NO perceptible lag AT ALL :))

git-svn-id: http://svn.inspircd.org/repository/trunk/inspircd@8714 e03df62e-2008-0410-955e-edbf42e46eb7