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_deque.py b/Lib/test/test_deque.py
index 63391af..d51a865 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -4,7 +4,7 @@
from weakref import proxy
import copy
import pickle
-from cStringIO import StringIO
+from io import StringIO
import random
import os