Log Message:
Update to 1.4:

#------------------------------------------------------------------------
# Version 1.04   Date: 2007/09/28
#------------------------------------------------------------------------

* Added the has_instance() method to return an existing instance without
  creating a new one.

* General cleanup of code, documentation and tests.

* Changed licence from Perl Artistic to the same terms as Perl itself
  (e.g. Artistic 2.0/GPL)