Merging the py3k-pep3137 branch back into the py3k branch.
No detailed change log; just check out the change log for the py3k-pep3137
branch.  The most obvious changes:

  - str8 renamed to bytes (PyString at the C level);
  - bytes renamed to buffer (PyBytes at the C level);
  - PyString and PyUnicode are no longer compatible.

I.e. we now have an immutable bytes type and a mutable bytes type.

The behavior of PyString was modified quite a bit, to make it more
bytes-like.  Some changes are still on the to-do list.
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index 088f4a0..97f639d 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -678,7 +678,7 @@
                 print(centdir)
             filename = fp.read(centdir[_CD_FILENAME_LENGTH])
             # Create ZipInfo instance to store file information
-            x = ZipInfo(str(filename))
+            x = ZipInfo(filename.decode("utf-8"))
             x.extra = fp.read(centdir[_CD_EXTRA_FIELD_LENGTH])
             x.comment = fp.read(centdir[_CD_COMMENT_LENGTH])
             total = (total + centdir[_CD_FILENAME_LENGTH]