Refactored Load IAR: created a generic mechanism to modify the SOG's as they are being loaded

Resolves http://opensimulator.org/mantis/view.php?id=6942
During Load OAR, fix the User and Group ID's in objects that are embedded in assets (previously only rezzed objects were fixed)

Resolves http://opensimulator.org/mantis/view.php?id=6942
In Load OAR: Zero isn't a valid Group ID

Resolves http://opensimulator.org/mantis/view.php?id=6943
In Load OAR, correctly restore group-owned objects

Resolves http://opensimulator.org/mantis/view.php?id=6943
Fixed parsing of coalesced objects if the XML starts with an XML Declaration ("<xml ...>")

Resolves http://opensimulator.org/mantis/view.php?id=6944