TODO

While this implementation of the fortuna random number generator is
complete, I intend to polish and extend the package over time.  My
aims are to make the user interface as intuitive as possible and to
reduce the probablity of accidentially using the package in an unsafe
way.  This file lists a possible directions for future work.

- Currently, the allocated source numbers for entropy sources wrap
  around modulo 256.  This may allow an attacker to route all entropy
  into the same source, by somehow allocating 255 fake-sources between
  every allocation of a real source.  Is this worth fixing somehow?

- Consider whether some of the recommendations of NIST Special
  Publication 800-90A [1] are worth implementing.  This includes, in
  particular, self-tests during operation.

    [1] http://csrc.nist.gov/publications/nistpubs/800-90A/SP800-90A.pdf

- Currently, the seed file is auto-saved every 10 minutes.  Should
  autosaving stop during periods where no random numbers are
  requested?