SF patch# 1770008 by Christian Heimes (plus some extras).

Completely get rid of StringIO.py and cStringIO.c.

I had to fix a few tests and modules beyond what Christian did, and
invent a few conventions.  E.g. in elementtree, I chose to
write/return Unicode strings whe no encoding is given, but bytes when
an explicit encoding is given.  Also mimetools was made to always
assume binary files.

Lib/distutils/tests/test_build_py.py

@@ -2,7 +2,7 @@
 
 import os
 import sys
-import StringIO
+import io
 import unittest
 
 from distutils.command.build_py import build_py
@@ -69,7 +69,7 @@ class BuildPyTestCase(support.TempdirManager,
         open(os.path.join(testdir, "testfile"), "w").close()
 
         os.chdir(sources)
-        sys.stdout = StringIO.StringIO()
+        sys.stdout = io.StringIO()
 
         try:
             dist = Distribution({"packages": ["pkg"],