* First pass at persistence support
* Fixed a chat crashing bug
* Remove avatars from the scene on logout
* Sanity check before adding objects to the scene in ObjectAdd
* Sanity check in CompleteAgentMovementHandler if the avatar is already in the scene
* Added ContainsKey() to DoubleDictionary
git-svn-id: http://libopenmetaverse.googlecode.com/svn/trunk@2245 52acb1d6-8a22-11de-b505-999d5b087335