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/fileinput.rst b/Doc/library/fileinput.rst
index 709237e..172a643 100644
--- a/Doc/library/fileinput.rst
+++ b/Doc/library/fileinput.rst
@@ -6,6 +6,9 @@
 .. moduleauthor:: Guido van Rossum <guido@python.org>
 .. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
 
+**Source code:** :source:`Lib/fileinput.py`
+
+--------------
 
 This module implements a helper class and functions to quickly write a
 loop over standard input or a list of files. If you just want to read or
@@ -44,11 +47,6 @@
 returns an accordingly opened file-like object. Two useful hooks are already
 provided by this module.
 
-.. seealso::
-
-   Latest version of the `fileinput Python source code
-   <http://svn.python.org/view/python/branches/release27-maint/Lib/fileinput.py?view=markup>`_
-
 The following function is the primary interface of this module: