Lock around read/write of ScenePresence.m_originRegionID to make sure that all threads are seeing the latest value and not a cached one.

There is a possibilty that some V2 teleport failures are due to the viewer triggered CompleteMovement thread not seeing the change of m_originRegionID by the UpdateAgent thread.
Make UUID.Zero resolve to "Unknown User" in user cache.

This is to avoid massive numbers of 'no user found' logs when user IDs are missing for some reason.
UUID.Zero should not be used for any user ID.
minor: Correct minor spelling mistake Reseting -> Resetting in HG Map module log message
minor: Add prefix to log message in LureModule
When giving items between avatars in different simulators, only add the item to the receiving avatar's inventory once.

When a user gives an item, the user's client sends an InventoryOffered IM message to its simulator. This adds the item to the receiver's inventory. If the receiver isn't in the same simulator then XMLRPC is used to forward the IM to the correct simulator. The bug was that the receiving simulator handled the message by calling OnInstantMessage() again, which added a second copy of the item to the inventory. Instead, the receiving simulator should only notify the avatar that the item was offered.
minor: Recomment out log message uncommented in previous cbdfe969
Preserve attachment point & position when attachment is rezzed in world

Patch taken from
http://opensimulator.org/mantis/view.php?id=4905
originally by Greg C.

Fixed to apply to r/23314 commit
ba9daf849e7c8db48e7c03e7cdedb77776b2052f
(cherry picked from commit 4ff9fbca441110cc2b93edc7286e0e9339e61cbe)
Don't use 'Indented' formatting for RpcXml responses.
(cherry picked from commit 93abcde69043b175071e0bb752538d9730433f1d)
* The last two are the the patch that Aleric wanted pulled from his repo. * Added GregC to CONTRIBUTORS.txt, Aleric was already in there. * There's some controversy, Some people have suggested that this could be stored in dynamic attributes instead of the database..    Melanie was wanting to pull from the avination repo but was asked to wait on committing anything new until the release.    The cherry-pick doesn't answer those questions.
Merge remote-tracking branch 'upstream/master'