Revision history:

0.08  Thu Jun 10 16:54:11 EDT 2010
    - Added match() for checking cron hits

0.07  Mon Mar 29 16:54:25 CST 2004
    - Patched next() and previous() to work with new DateTime::Set

0.06  Tue Dec 30 14:28:32 CST 2003
    - Added user-mode auto-detection
    - Added original() method to return original
      unparsed cron strings

0.05  Tue Nov 11 22:40:16 CST 2003
    - Retains command and user strings if present
    - Switched to named parameters for constructors
    - Added 'user_mode' parameter for crontab formats
      that include user names before the command.
    - Added command() and user() methods

0.04  PAUSE fodder

0.03  Wed May  7 17:09:38 EDT 2003
    - more edge cases detected/prevented
    - dependencies added
    - removal of 'our'

0.02  Fri May  2 00:22:52 EDT 2003
    - changed API
    - fixed some boundary cases
    - streamlined, added some helper classes with cron sets
    - CPAN

0.01  Tue Apr 22 19:52:56 EDT 2003
    - initial release
