Add functions PyUnicode_Append() and PyUnicode_AppendAndDel() that mirror
PyString_Concat() and PyString_ConcatAndDel() (the name PyUnicode_Concat()
was already taken).

Change PyObject_Repr() to always return a unicode object.

Update all repr implementations to return unicode objects.

Add a function PyObject_ReprStr8() that calls PyObject_Repr() and converts
the result to an 8bit string.

Use PyObject_ReprStr8() where using PyObject_Repr() can't be done
straightforward.
diff --git a/Objects/funcobject.c b/Objects/funcobject.c
index 0069fc1..6f17e7a 100644
--- a/Objects/funcobject.c
+++ b/Objects/funcobject.c
@@ -574,7 +574,7 @@
 static PyObject*
 func_repr(PyFunctionObject *op)
 {
-	return PyString_FromFormat("<function %s at %p>",
+	return PyUnicode_FromFormat("<function %s at %p>",
 				   PyString_AsString(op->func_name),
 				   op);
 }