Returns a copy of the projection matrix

def copy(self):
        """Returns a copy of the projection matrix"""
        params = {}
        for key, val in self.__dict__.items():
            if 'matrix' not in key:
                k = key[1:] if key[0] == '_' else key
                params[k] = val
        # params = {param: params[param] for param in params}
        return self.__class__(**params)