As discussed in D1734#38749, this will make vector displacement fit in,
and is also more convenient / user friendly than using a vector math node
to tweak displacement scale.
It's backwards compatible by inserting this node automatically in existing
files, and moving the hardcoded 0.1 scaling into the distance socket.
There's few issue still:
- Perhaps the name of the node should be changed to something like "Normal Displacement" or "Scalar Displacement"?
- Changing displacement socket types did not work correct, and was fixed in rB79563d2a33ef. However releases before 2.79a will hit an assert when rendering files saved with this change. It will not crash or cause any issues because we don't use the value of this socket, but it's still weak. Is this acceptable?
- The original reason for the 0.1 scale was that bump and displacement looked very different with the same values. That is still case, and it would be good if we could figure out why and address the real problem, ideally as part of this change.