Applies the change to the selection model: calls GraphSelectionModel.cellRemoved for each cell in removed, then GraphSelectionModel.cellAdded for each cell in added. Swaps added and removed so a subsequent call undoes the change, then fires InternalEvent.CHANGE on the selection model.
WARN: because of the swap, the added and removed properties of the fired event refer to the
post-swap arrays — the event's added contains the cells just removed from the selection, and
vice-versa. This naming is preserved for historical reasons.
Action to add and remove cells to/from the selection of a GraphSelectionModel.