* Clear cached name, groupName in Avatar when an ObjectUpdate has new NameValues.
* Some message paths didn't maintain group title, while others did. (Although I don't think that affects this implementation.)
* In the proxy, do send an avatar update for group title changing to empty string.
* ActivateGroup and RequestAgentDataUpdate commands from UI to app to proxy to sim.
* Message back to UI OnAgentDataUpdate, so that we can tell whether a given group of this agent is already active.
Add logic to copy region size info (if supplied) into Simulator class on instance creation.
Add region size fields to definitions of LoginResponse, EnableSimulator, TeleportFinishMessage, CrossedRegionMessage.
Add constants Simulator.DefaultRegionSizeX=256 and Simulator.DefaultRegionSizeY=256
Add display of region size in "RegionInfo" TestClient command
