(1) The corresponding points in the original and cloned shapes
can be connected through KoPathPointIndex. Use
`cloned->pointByIndex(origIndex)` to obtain the corresponding point
in the cloned shape. Since we will also need to record the shape the
point belongs to, we can use KoPathPointData which combines these two.

(2) KoPathToolSelection has its own shape selection, and it is vital
to map it as well, since KoPathToolSelection::update() will remove any
point that is not a part of its selectedShapes().