Log Message:
Update to 0.8.0:
  * Support package priorities in want list.
  * Clean after install (not just after upgrade).
  * Enforce certain core wants (e.g. pkg_install)
    priorities to be high.
  * Honor PKGMANAGER_DEBUG environment variable.
  * Rename 'showwants' command to 'show-wants' for consistency.
  * Add a proper manpage.