Returns the plugin renderer based on the inputed name.
        
        :param      name | <str>
        
        :return     <XChartRenderer> || None

def plugin(name):
        """
        Returns the plugin renderer based on the inputed name.
        
        :param      name | <str>
        
        :return     <XChartRenderer> || None
        """
        cls = XChartRenderer._plugins.get(name)
        if cls:
            renderer = cls()
            renderer.setName(name)
            return renderer
        return None