World now caches and tracks member statuses so it can send them to zones
that request them on startup. Prior to this the cle would be searched in
world for every zone startup caching request, now it's only searched once
when a new expedition is created.
Bulk loading statuses removed since it would only be needed on world
startup now and likely have no clients in the client list anyway.
This also lets world choose non-linkdead members on expedition leader
changes and better detect when a leader change needs to occur
This should eliminate race conditions caused by zones trying to set
a leader when members in different zones quit at the same time
Zone still detects when leader goes offline to trigger a change
since it's easier than having world process expedition member status
updates and perform expedition lookups
