Added usage of HistoryChange in undo- and redo method, such that observers may observe that the model history changes in relation to undos and redos.
Added usage of HistoryChange in undo- and redo method, such that
observers may observe that the model history changes in relation to
undos and redos.

Signed-off-by: Jakob Brandsborg Ehmsen <387ed33cc9ebf98b733caa2520baacd616b28aa5@gmail.com>
jakobehmsen/dynamake