add initial inverse dynamics example skeleton, with urdf and programmatically created btMultiBody.

disabled in Bullet/examples/ExampleBrowser/ExampleEntries.cpp

examples/Importers/ImportURDFDemo/MyMultiBodyCreator.h

@@ -21,6 +21,7 @@ struct GenericConstraintUserInfo
 
 class MyMultiBodyCreator : public MultiBodyCreationInterface
 {
+protected:
 
 	btMultiBody* m_bulletMultiBody;