Record for module type declarations.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/extension_points@13358 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Attribute has structure/signature item.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/extension_points@13359 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Document the changes on the branch.

git-svn-id: http://caml.inria.fr/svn/ocaml/branches/extension_points@13360 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02