More bug fixes on group chat
Clarification on docs of .ini.examples for Groups (again)
More on group chat: only root agents should subscribe to OnInstantMessage, or else they'll see an echo of their own messages after teleporting.
This makes group search work (Groups V2).
This makes people search work.
Added BasicSearchModule.cs which handles OnDirFindQuery events. Removed that handler from both Groups modules in core, and replaced them with an operation on IGroupsModule.
Removed commented lines and useless debug message
Fix an issue where HG members of groups weren't seeing the entire membership for group chat.
Same issue as previous commit.
Same issue.
Changing the visibility test in groups service to be UUID.Zero.ToString() instead of "all" because some paths in the code assume there's a UUI in the RequestingAgent string.
Group chat: guard against duplicate sends
Group chat: prevent a situation where dupe IMs could occur.
Groups: Better warning messages to the user.
Make "abnormal thread terminations" into "ClientLogoutsDueToNoReceives" and add this to the StatsManager

This reflects the actual use of this stat - it hasn't recorded general exceptions for some time.
Make the sim extra stats collector draw the data from the stats manager rather than maintaing this data itself.
Fix issue just introduced in 8efe4bfc2ed7086e9fdf4812297e6525f955f6ac where I accidentally left in a test line to force very quick client unack
minor: Add timeout secs to connection timeout message.  Change message to reflect it is a timeout due to no data received rather than an ack issue.
BulletSim: make density display and return value consistant with how
the simulator expects it (scaled to 100kg/m^3).
BulletSim: test method for debugging of extended physics script operations.
BulletSim: distribute vehicle physical settings to all members of
a linkset. Enables constraint based linksets.
Rename some internal variables to clarify whether values world or
vehicle relative.