Revision history for Tk::MARC.
------------------------------
1.4 January 20, 2004
    - croak on missing -record in Tk::MARC::Record
    - croak on missing -field or -tag / -subfields
      in Tk::MARC::Field
    - croak on missing -field and -label in
      Tk::MARC::Subfield
    - croak on missing -field in Tk::MARC::Indicators
    - croak on missing -record in Tk::MARC::Leader
    - more tests

1.3 January 19, 2004
    - added a whack of test cases

1.2 January 18, 2004
    - moved the confusing lib/Tk-MARC.pm to lib/Tk/MARC.pm
    - had the documentation-only MARC.pm 'use Tk::MARC::Record',
      so users can just say 'use Tk::MARC' rather than
      'use Tk::MARC::Record'
    - added another sample app: 
      pl/muse.pl - the MARC un-optimized sample editor

1.1 January 17, 2004
    - renamed Tk::MARC::record     to Tk::MARC::Record
    - renamed Tk::MARC::field      to Tk::MARC::Field
    - renamed Tk::MARC::subfield   to Tk::MARC::Subfield
    - renamed Tk::MARC::indicators to Tk::MARC::Indicators
    - renamed Tk::MARC::leader     to Tk::MARC::Leader

1.0 January 16, 2004
    - original version, slurped the individual Tk::MARC::*
      packages into one module.