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/test/test___all__.py

@@ -36,7 +36,6 @@ class AllTest(unittest.TestCase):
         self.check_all("Queue")
         self.check_all("SimpleHTTPServer")
         self.check_all("SocketServer")
-        self.check_all("StringIO")
         self.check_all("UserString")
         self.check_all("aifc")
         self.check_all("base64")