This replaces the boolean Offset input in the Set Position node with
a vector input. This makes the node easier to use. Using a "Position"
input as an "Offset" sounds wrong anyway.
The Position and Offset inputs are evaluated at the same time.
The versioning only works correctly when the Offset input was not connected
to something else before.
Differential Revision: https://developer.blender.org/D12983
b3ca926aa8