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_sax.py b/Lib/test/test_sax.py
index 0d76cbb..e2639fa 100644
--- a/Lib/test/test_sax.py
+++ b/Lib/test/test_sax.py
@@ -12,7 +12,7 @@
XMLFilterBase
from xml.sax.expatreader import create_parser
from xml.sax.xmlreader import InputSource, AttributesImpl, AttributesNSImpl
-from cStringIO import StringIO
+from io import StringIO
from test.test_support import findfile, run_unittest
import unittest
import os