Re-instated virtual declaration for Csound member functions.
Re-instated virtual declaration for Csound member functions.

csound/csound,ketchupok/csound,csound/csound,ketchupok/csound,csound/csound,csound/csound,ketchupok/csound,csound/csound,csound/csound,ketchupok/csound,ketchupok/csound,csound/csound,csound/csound,ketchupok/csound,ketchupok/csound,csound/csound,ketchupok/csound,ketchupok/csound,ketchupok/csound,csound/csound