translate_polymorphic_Q_object: fixed test case, and made the function a member of PolymorphicObject.

Minor test fixes: warnings fixed, test_tool.py renamed as it's no test

CHANGES.html

@@ -276,6 +276,9 @@ more simple and intuitive use:</p>
 &gt;&gt;&gt; ModelA.objects.all()
 </pre>
 </li>
+<li><p class="first">added member function:
+<tt class="docutils literal">normal_q_object = ModelA.translate_polymorphic_Q_object(enhanced_q_object)</tt></p>
+</li>
 <li><p class="first">misc changes/improvements</p>
 </li>
 </ul>