Merging from tim-doctest-branch, which is now closed.

This primarily adds more powerful ways to work with unittest, including
spiffy support for building suites out of doctests in non-Python
"text files".

Lib/test/sample_doctest.py

@@ -0,0 +1,66 @@
+"""This is a sample module that doesn't really test anything all that
+   interesting
+
+It simply has a few tests, some of which suceed and some of which fail.
+
+It's important that the numbers remain constance, as another test is
+testing the running of these tests.
+
+
+>>> 2+2
+4
+"""
+
+
+def foo():
+    """
+
+    >>> 2+2
+    5
+
+    >>> 2+2
+    4
+    """
+
+def bar():
+    """
+
+    >>> 2+2
+    4
+    """
+
+def test_silly_setup():
+    """
+
+    >>> import test.test_doctest
+    >>> test.test_doctest.sillySetup
+    True
+    """
+
+def w_blank():
+    """
+    >>> if 1:
+    ...    print 'a'
+    ...    print
+    ...    print 'b'
+    a
+    <BLANKLINE>
+    b
+    """
+
+x = 1
+def x_is_one():
+    """
+    >>> x
+    1
+    """
+
+def y_is_one():
+    """
+    >>> y
+    1
+    """
+
+def test_suite():
+    import doctest
+    return doctest.DocTestSuite()