more correct creation and edit times for entities
accept changes with the same Edit timestamp
handle case where obj at rest but still falls
set _lastEdited to _created rather than to zero
merge upstream/master into andrew/thermonuclear
fix typo that broke the build
cleanup of EntityItem::_created timestamp logic

EntityItem::_created initializes to 0 in ctor
and must be set either by EntityItemProperties (via server update)
or manually whenever a script creates a fresh entity
fixing derived classes to use new EntityItem API

remove 'forceCopy' argument in EntityItem::setProperties()
merge upstream/master into andrew/thermonuclear
merge upstream/master into andrew/thermonuclear
Merge pull request #3980 from AndrewMeadows/thermonuclear

more correct creation and edit times for entities