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/shelve.rst b/Doc/library/shelve.rst
index 4f2d94b..7a70ff4 100644
--- a/Doc/library/shelve.rst
+++ b/Doc/library/shelve.rst
@@ -7,16 +7,16 @@
 
 .. index:: module: pickle
 
+**Source code:** :source:`Lib/shelve.py`
+
+--------------
+
 A "shelf" is a persistent, dictionary-like object.  The difference with "dbm"
 databases is that the values (not the keys!) in a shelf can be essentially
 arbitrary Python objects --- anything that the :mod:`pickle` module can handle.
 This includes most class instances, recursive data types, and objects containing
 lots of shared  sub-objects.  The keys are ordinary strings.
 
-.. seealso::
-
-   Latest version of the `shelve module Python source code
-   <http://svn.python.org/view/python/branches/release27-maint/Lib/shelve.py?view=markup>`_
 
 .. function:: open(filename[, flag='c'[, protocol=None[, writeback=False]]])