Update to 0.56.0

  Version 0.56.0, by Aleksey Cheusov, Sun, 28 Aug 2011 12:05:00 +0300

  pkg_cmp_summary:
    - New option -O was added for specifying fields for
      output without using them for comparison

  Version 0.55.0, by Aleksey Cheusov, Sat, 27 Aug 2011 20:14:53 +0300

  pkg_lint_summary:
    - New option -f option was added that checks files in PLIST
      fields given on input and warns about files common for several
      packages.
    - New option -p option was added for specifying prefix directory
      used by option -l.
    - New option -n was added that analyses PLIST and CONFLICTS
      fields in input summaries and outputs unregistered conflicts.
    - New option -s was added that checks OPSYS, OS_VERSION and
      MACHINE_ARCH fields given on input and warns if they differ from
      that of running system (uname -srm).

  pkg_cmp_summary:
    - New options -a and -A were added for specifying fields for
      comparing in addition to package versions.
    - New option -E was added. It works together with -A and changes
      its output.
    - Options -c and -b were reimplemented using more generic -a.
    - Examples section was added to pkg_cmp_summary.1

  pkg_bin_summary:
    - New option -e option was added for effectively using
      pkg_bin_summary with xargs (xargs -r is not portable).
    - New option -k was added for enriching binary package summaries
      with checksums using algorithms supported by digest(1)

  pkg_digger_backend:
    - Mixed -1|-3|-9 options are now handled correctly.

  pkg_summary2leaves:
    - When no files are given as arguments (stdin),
      pkg_summary2leaves outputs an error message.

  Regression tests have been reorganized. One test - one file.

  Some manual pages were updated and improved.

(cheusov)