* The rest of the backend support for simplistic experiment duplication,
  either from an existing (current) experiment, or from a specific
  archive revision of a current or terminated experiment.

* Rework the swapmod code so that the archive is committed at the exact
  end of the swapout phase. This required adding (and moving) some code
  from swapexp to tbswap sine that is where the actual swapout/swapin
  happens during a swapmod

* Add a special directory called "archive" to the experiment
  directory, which is a place where users can store stuff they want
  saved away. This will eventually be a user defined set of
  directories, but this was good for getting the basic mechanism in
  place. Note that the when the contents of this directory are copied
  out for placement into the archive, it is an exact copy made with
  rsync.

* No longer "clean" the contents of the temporary store between
  commits of the archive. This was creating a lot of headaches, and
  was also causi...