Implement update Event functionality.

[jamoore]

Currently only the creation Events are being linked from each entity. Update Events are recorded but not on each row.

[jmoore]

This is important and tied to the security system (#114) . Will rev up in milestone:3.0-M2

[jmoore]

Discussion during ​ConfCall Sep. 7, 2006 decided to only store last modification.

[jmoore]

r962 implements the update event logic:

• finally sets updateEvent to not null
• adds 0 update_id to data.vm and common/build.xml
• added setUpdateEvent() call in CurrentDetails (transient)
• added a "pre-update" event listener to ~asynch. update the update event (managed)
• added security checks in BasicSecuritySystem
• misc: refactored more methods out to HibernateUtils

The semantics are such that no one can manually alter the update event of an entity, but if the entity is updated (or locked) that it's update event will be automagically incremented to the current event.

[jmoore]

r962 caused #366, leaving in place because the update functionality is more important.

[jmoore]

Note: automagically incrementing the update event is similar to updating the version. In fact, as long as versions are broken (#118) this may indeed help us catch many of the spurious deletes.

Could it completely replace versioning?

[jmoore]

See #118 for all further discussion on versions v. updateEvent. Closing.