Update to 0.20
    
    - New upstream release 0.20
      - Methods were renamed for brevity: s/_package//
      - Convert Package::Stash into a module which loads either the XS or pure perl
        implementation, depending on what's available
      - Use Test::Fatal instead of Test::Exception
      - Use Dist::CheckConflicts
      - Silence deprecation warnings for the method renaming for now
    - New script and manpage: package-stash-conflicts
    - New modules and manpages: Package::Stash::Conflicts and Package::Stash::PP
    - New build requirements:
      - perl(Dist::CheckConflicts)
      - perl(Package::DeprecationManager)
      - perl(Package::Stash::XS)
      - perl(Test::LeakTrace)
      - perl(Test::Requires)
      - perl(Test::Script)
    - Update patches for old ExtUtils::MakeMaker and Test::More versions
    - Add new patch to work around absence of Test::Requires in EPEL-4
    - Require perl(Package::Stash::XS) for performance and consistency
    - Manually provide perl(Package::Stash::Conflicts), hidden from auto-provides