- added "Optional Extensions to the Importer Protocol" section
- fixed flaw in the importer protocol: i.find_module() will now receive
the package.__path__ (or None for a plain module) as an additional
argument, if it's installed on sys.meta_path. This is needed to
be able to add a hook that implements the full sys.path/pkg.__path__
semantics. See also footnote [7]. The patch on sf will be updated
shortly to match the new version of the PEP.