Notes on looking at the merge diffs:


0.8.2 in OnMakeRoot, does SendAgentGroupDataUpdate. 0.9.0 removes this with comment
    that this is a wrong thread to do this and that viewer ignores this message.
    This update missing causes problems (Mantis 7920 and 7915)
    Restored the SendAgentGroupDataUpdate with a comment.
The code for group updates was refactored differently in the two versions:
    0.8.2 added an OnAgentDataUpdateRequest for extensibility and used that
        in SendAgentGroupDataUpdate
    SendAgentGroupDataUpdate was changed to send to optionally update other clients
    0.8.2 put logic for sending update via Caps in GroupsModule.
        Merge properly put it in LLClientView
    0.9.0 cleaned up update with SendAgentGroupDataUpdate and SendDataUpdate
8.2 commented out OnClientClosed event commenting that InstantMessageModule doesn't do this
    Merge added logic to OnClientClosed to find who to send the update to
        The original problem was that the event was fired when there were several
            possible destination
OnAgentDataUpdateRequest: 0.9.0 calls SendAgentGroupUpdate while 0.8.2 calls
    both SendAgentGroupUpdate and SendScenePresenceUpdate. 0.9.0 has comment that
    region arrival will send the group title. Keep lookout for not getting group titles.
0.9.0 sends group updates to all clients more often than 0.8.2.
    Could be extra traffic when changing groups but probably not a problem