added __all__ lists to a number of Python modules
added test script and expected output file as well
this closes patch 103297.
__all__ attributes will be added to other modules without first submitting
a patch, just adding the necessary line to the test script to verify
more-or-less correct implementation.
diff --git a/Lib/StringIO.py b/Lib/StringIO.py
index 5fac590..bc5e9e2 100644
--- a/Lib/StringIO.py
+++ b/Lib/StringIO.py
@@ -34,6 +34,8 @@
 except ImportError:
     EINVAL = 22
 
+__all__ = ["StringIO"]
+
 EMPTYSTRING = ''
 
 class StringIO: