Returns the plugins for the given class.
        
        :param      enabled | <bool> || None
        
        :return     [<Plugin>, ..]

def plugins(cls, enabled=True):
        """
        Returns the plugins for the given class.
        
        :param      enabled | <bool> || None
        
        :return     [<Plugin>, ..]
        """
        cls.loadPlugins()
        plugs = getattr(cls, '_%s__plugins' % cls.__name__, {}).values()
        if enabled is None:
            return plugs

        return filter(lambda x: x.isEnabled() == enabled, plugs)