Issue #10783: struct.pack() doesn't encode implicitly unicode to UTF-8

 * Replace "bytes" by "bytes object" in struct error messages
 * Document the API change in What's new in Python 3.2
 * Fix test_wave
 * Remove also ugly implicit conversions in test_struct
diff --git a/Doc/whatsnew/3.2.rst b/Doc/whatsnew/3.2.rst
index b317896..51e1d86 100644
--- a/Doc/whatsnew/3.2.rst
+++ b/Doc/whatsnew/3.2.rst
@@ -1705,3 +1705,7 @@
 
   (Contributed by Georg Brandl and Mattias Brändström;
   `appspot issue 53094 <http://codereview.appspot.com/53094>`_.)
+
+* :func:`struct.pack` doesn't encode implicitly unicode to UTF-8 anymore: use
+  explicit conversion instead and replace unicode literals by bytes literals.
+