Checkpoint. Manipulated things so that string literals are always

unicode, and a few other compensating changes, e.g. str <- unicode,
chr <- unichr, and repr() of a unicode string no longer starts
with 'u'.  Lots of unit tests are broken, but some basic things
work, in particular distutils works so the extensions can be built,
and test_builtin.py works.

Python/ast.c

@@ -3187,7 +3187,7 @@ parsestr(const node *n, const char *encoding, int *bytesmode)
         }
     }
 #ifdef Py_USING_UNICODE
-    if (unicode || Py_UnicodeFlag) {
+    if (!*bytesmode) {
         return decode_unicode(s, len, rawmode, encoding);
     }
 #endif