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.
diff --git a/Lib/test/test_minidom.py b/Lib/test/test_minidom.py
index cc637d0..fb3b098 100644
--- a/Lib/test/test_minidom.py
+++ b/Lib/test/test_minidom.py
@@ -4,7 +4,7 @@
import sys
import pickle
import traceback
-from StringIO import StringIO
+from io import StringIO
from test.test_support import verbose, run_unittest, TestSkipped
import unittest