Adjusted plotting tool such that transactions are tracked from the mouse
is pressed, a model is plotted and till either
- a specific kind of model is chosen to be created - in this case a
composite transaction is made, which is used during undo/redo instead of
the isolated single transactions
- the creation is canceled - in this case, the tracked transactions are
rolled

Signed-off-by: Jakob Brandsborg Ehmsen <jakobehmsen.github@gmail.com>