Return user-created Go2Color object or create one.

def _init_objcolor(self, node_opts, **kwu):
        """Return user-created Go2Color object or create one."""
        objgoea = node_opts.kws['dict'].get('objgoea', None)
        # kwu: go2color go2bordercolor dflt_bordercolor key2col
        return Go2Color(self.gosubdag, objgoea, **kwu)