[Catalog-sig] Wheel format now supported

[Daniel Holth]

The pip developers are interesting in supporting wheel after their
upcoming release. Wheel installations work as long as you are using
distribute >= 0.6.28. It works with virtualenv, but no one has tried
to write what would surely be called zc.recipe.wheel for buildout.

After you install a wheel, it is just a PEP-376 compatible
distribution, so it stores its metadata in a .dist-info directory
instead of in .egg-info.