GeoShapeShift - Collapse a chain of GeoShapeShifts into one
I've seen in the muon geometry a couple of places where we have
GeoShapeShift ( GeoShapeShift (GeoShapeShift (GeoShapeShift of something
That's producing an unneccassry call twoer given that we're only interested in the summarized shift. This little checks at the construction stage of the GeoShapeShift whether the given shape is another shift. If so, then it combines the two transformations and takes the operand of the child.