Renamed ParseGlobal*() methods to ParseGroup*().
Implemented use of template class unique_ptr<>
Renamed several method names and make use of the unique_ptr<> class template.
Refactored code to use the Constant class rather than the old deprecated
Argument class.
Implement use of the template class unique_ptr<> in the FunctionCall class.
Once again use the Constant class rather than the old deprecated Argument class.
Removed deprecated class.
Removed @todos which were already implemented and change the constness of the
returned pointer types.
Make use of the unique_ptr<> template class.

I also include the copy constructor for the Mockup* family of classes.