TODO

* Update the samples, Ruby doesn't come with Tk any more.
* Rolling snapshots, with age limit
* Configurable log marshaller (or use the snapshot marshaller?)
* Write a document about the different marshallers, for app. developers.
  (or drop support for them)

* Introduce an object representing a log directory
* Move recovery out of DefaultSnapshotMadeleine entirely
* Write an example with a web server (see madeleine-rack)

* Replace filesystem with mock objects for unit testing.
* ClockCommand
* Integrate batched-writes in SnapshotMadeleine
* More sample code
* More documentation
* Rollback
* Handle premature EOF in logs (unless we're already there)

* A way to stream larger files into the system, possibly stored
  within the command log?

* .ruby-version file