Update to 0.21
    
    - New upstream release 0.21
      - Remove useless use of UNIVERSAL::isa (CPAN RT#105948)
    - Classify buildreqs by usage
    - Drop obsoletes/provides for old tests sub-package
    - Drop %defattr, redundant since rpm 4.4
    - Don't need to remove empty directories from the buildroot
    - Don't use macros for common commands
    - Make %files list more explicit