virtual int add_quantity(int delta, int shapenum, int qual = -359, int framenum = -359, int dontcreate = 0)
virtual int add_quantity(int delta, int shapenum, int qual = c_any_qual, int framenum = c_any_framenum, int dontcreate = 0)
	virtual int add_quantity(int delta, int shapenum, int qual = -359,				int framenum = -359, int dontcreate = 0)		{ return delta; }