EVT_LOGOUT hooks are now called with the thread's current

EVT_LOGOUT hooks are now called with the thread's current
CitContext set to that of the session being logged out, even when
killing a session administratively.  This allows the identity of the
user to be passed along to module hooks.  This fixes the problem in
the Jabber server where buddy 'ghosts' whould remain visible to
clients if the user disconnected without logging off.