Do not return non-const pointers to elements of const containers
- make the return type of 'containedObject() const' a const pointer to the relevant element of the container
- add a non-const 'containedObject()' method which returns a non-const pointer to the relevant element of the container
- this makes the behaviour of ObjectContainerBase (and its derived classes) consistent with STL containers
Edited by Gerhard Raven