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.
