Megapatch that fixes/adds: friend offer/deny/accept, friendship termination,

on-/offline updates, calling cards for friends.
This adds methods in the DB layer and changes the MessagingServer, so a full
update (incl. UGAIM) is necessary to get it working. Older regions shouldn't
break, nor should older UGAIM break newer regions, but friends/presence will
only work with all concerned parts (UGAIM, source region and destination
region) at this revision (or later).
I added the DB code for MSSQL, too, but couldn't test that.
BEWARE: May contain bugs.

OpenSim/Framework/IClientAPI.cs

@@ -925,6 +925,8 @@ namespace OpenSim.Framework
         void SendAcceptCallingCard(UUID transactionID);
         void SendDeclineCallingCard(UUID transactionID);
 
+        void SendTerminateFriend(UUID exFriendID);
+
         void KillEndDone();
     }
 }