def movePluginsTop(plugin_type, ids_to_move):
    """ Move a set of plugins to the "top" in their list.

        o 'plugin_type' must be one of the known types, else raise KeyError.

        o 'ids_to_move' must be a sequence of ids of current plugins
          for that type.

          - If any item is not the ID of a current plugin, raise ValueError.
          - Moving one plugin to top has obvious result;
            moving more than one plugin to top puts them one by one at the top
            iow, last in the list gets to top
        """
