v0.3:
    Fixed wrong class generation in case there were no attributes to 
    be initialized;

    Added support for XMI files (tested only with XMI files generated 
    by Umbrello);

    Operations defined as "pk" at UML design are not an argument at class
    initialization anymore (supposing they are auto-incremented). This may
    change in the future by adding something more explicit to the "pk"
    operation (like "auto-increment" or "ai" or something like that).
