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/Modules/_sqlite/cache.c b/Modules/_sqlite/cache.c
index 829c175..2f50e6a 100644
--- a/Modules/_sqlite/cache.c
+++ b/Modules/_sqlite/cache.c
@@ -241,12 +241,12 @@
         if (!fmt_args) {
             return NULL;
         }
-        template = PyString_FromString("%s <- %s ->%s\n");
+        template = PyUnicode_FromString("%s <- %s ->%s\n");
         if (!template) {
             Py_DECREF(fmt_args);
             return NULL;
         }
-        display_str = PyString_Format(template, fmt_args);
+        display_str = PyUnicode_Format(template, fmt_args);
         Py_DECREF(template);
         Py_DECREF(fmt_args);
         if (!display_str) {