Uniform scale is superior to non-uniform scale in that it works with
parenting without causing shear. Thus it is a valid desire in some
cases to turn arbitrary scale into guaranteed uniform scale.
Implementing this in the Copy Scale constraint allows one for instance
to 'inherit scale as uniform' by disabling Inherit Scale, and using
Copy Scale from parent with Offset and Make Uniform.
Reviewers: brecht
Differential Revision: https://developer.blender.org/D5614
497297850a