bitbake-layers: improve show-overlayed output

bitbake-layers: improve show-overlayed output

Make the following improvements to the show-overlayed subcommand:

* Show recipes that are overlayed when the version is higher or lower,
  not just when it is the same. This gives a much better picture of the
  influence each layer is having over the metadata used for building.
  This can be disabled with the -s option if you just want to see
  recipes with the same version as before.
* Default to showing name (PN), layer and version rather than the full
  path and filename. The old style formatting can be used by specifying
  the -f option.
* Mark skipped recipes as such in the output, and print them in the
  correct sorted place in the list rather than at the end
* Prefix/suffix title line with === so it can be filtered out easily in
  shell scripts if desired

(Bitbake rev: 43b473275d3cb2e60a14e4a52cdc4654b3f4e5e7)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>