LP #642728: Fixed TypeError on nested multi part messages in MailHost. Thanks to Mail Derstappen for the patch!

- added forward-compatibility shim for UserFolder (this makes it easier to write CMF migration code)

make sure that the browser:view directive doesn't clobber security declarations for attributes which are not included in allowed_attributes or allowed_interface but which already have security declarations in a base class's security info. This is needed to provide access to, e.g., restrictedTraverse on views that subclass Traversable

  indexable value for an object in PluginIndexes.common.UnIndex

  specific listening IP is configured for the HTTP server, do a
  socket lookup to show the current server's fully qualified name.

  which prevented renaming files and folders via FTP.

  exceptions encountered during path traversal.

  url_quote_plus and url_unquote_plus to handle unicode strings.