2010-03-16 (0.1.8)
    * Disabled building of gem spec file.
    * Reorganised documentation.
    * Fixed an unncessary check.
2009-07-19 (0.1.7)
    * Create a gem spec file.
    * Some cleanup.
2008-12-01 (0.1.6)
    * Reuse last value more.
    * Re-indented code.
2007-04-17 (0.1.5)
    * Added version.
    * Better caching for factorial.
2006-03-11 (0.1.4)
    * Applied two bugfixes. Thanks go to Roel Harbers <roel@roelharbers.com>
      for the report.
    * Disabled autorequire for gem.
2004-07-16 (0.1.3)
    * Moved gemspec into Rakefile
    * Cleaned up a bit.
2004-07-16 (0.1.2)
    * Added Permutation.for factory method for convenience.
    * Raising ArgumentError instead of simple strings.
2004-07-03 (0.1.1)
    * First Rubyforge version.
    * Supports rubygems now.
2004-04-29 (0.1.0)
    * Initial version
