more correct creation and edit times for entities

Fixing some bugs that I introduced when I split out EntityItem::_lastSimulated time from EntityItem::_lastUpdated and EntityItem::_lastEdited.

The bugs were not noticeable under normal conditions, but became noticeable when trying to get results from one physics simulation (bullet) to be relayed across the EntityServer and into another interface instance that was running a simpler simulation.  The update packets from the EntityServer were getting rejected at the receiving end because the accompanying _lastEdited time was too old.
The fact that we didn't set LastEdited in the properties here would cause the recipient EntityItem to get its _lastCreated value reset to zero, which would compute large "time since last edit" values relayed to recipient interfaces through the EntityServe, which would cause numerical error on the quint64 value range which would result in _lastEdited values in the future on the receiving end, which would then refuse to accept any more updates from the EntityServer since their LastEdit times would be in the past as far as these bugged EntityItem's were concerned.   This probably fixes  a few bugs where one person would sometimes change an entity and others would not see the result on their end.