Backport source links from 3.x.

Existing links have been updated to use the new reST role.  In some
files, I have also made cosmetic changes to the header.
diff --git a/Doc/library/functools.rst b/Doc/library/functools.rst
index 787c000..10c984f 100644
--- a/Doc/library/functools.rst
+++ b/Doc/library/functools.rst
@@ -8,18 +8,16 @@
 .. moduleauthor:: Nick Coghlan <ncoghlan@gmail.com>
 .. sectionauthor:: Peter Harris <scav@blueyonder.co.uk>
 
-
 .. versionadded:: 2.5
 
+**Source code:** :source:`Lib/functools.py`
+
+--------------
+
 The :mod:`functools` module is for higher-order functions: functions that act on
 or return other functions. In general, any callable object can be treated as a
 function for the purposes of this module.
 
-.. seealso::
-
-   Latest version of the `functools Python source code
-   <http://svn.python.org/view/python/branches/release27-maint/Lib/functools.py?view=markup>`_
-
 The :mod:`functools` module defines the following functions:
 
 ..  function:: cmp_to_key(func)