mismatch between getTransform - zoomAbs

[Cesare Pautasso]

I am trying to restore the state of a panzoom instance

// memento the current transformation state
state = instance.getTransform()

// recover the state
instance.zoomAbs(state.x, state.y, state.scale)

the instance doesn't go back to the same state.

[Richard Leddy]

While looking at the code I might as well comment.
getTransform might return Object.assign({},transform), but it returns transform.
However, if it does return the copy (no lower levels ... simple object), then the handlers will not be able to manipulate transforms by changing field values explicitly.

Internally, transform is a global value always containing the current transform state.

Perhaps there needs to be another method.