I should be able to roll back Things to a previous state from a particular date

Summary: The notion here is a very specialized but generally useful version of rollback: a function that, given a datetime, and a set of Things, rolls them all back to their state right before that point.

Eric suggests that, since this is a pretty dangerous command, making it console-only might be useful. That seems like a nicely plausible limitation, although it will probably sometimes want to be coupled with a filter feeding in the OIDs to be rolled back. Does that work?

This should be a complete rollback, including last modification time.