* New utility function xmpp_is_visible(), used to determine whether any given session...

* New utility function xmpp_is_visible(), used to determine whether any given session in the wholist is visible to the current user and capable of receiving instant messages.  This eliminates duplicate code in three different places.
* The XMPP mortuary is functionally complete and does appear to be working properly.  Upon connecting, an XMPP client now receives 'buddy delete' messages for any buddy he has ever seen, minus the ones who are online right now.  This should effectively eliminate the accumulation of 'ghost' buddies on large public access systems like Uncensored.