0.2.0:
  - fixed open mode in transaction (must always be 'rb+' not 'rb')
  - added default timeout to #snapshot
0.1.0:
  - general clean up and some commenting
  - mods to #transaction and #snapshot to make them more robust in face of
    unexpected errors
  - if using nfslocking a file is made containing the node, pid, ppid, and time
    the lock was obtained so it's easy to clean up if some sick process on some
    node holds the lock
0.0.0:
  - initial version