Change default studiolight to replace current default matcap.
We cannot make it match perfectly because the matcap is
projected using some kind of reflection projection and does not
really map to a lambertian surface model.
So instead of matching the previous matcap we try to get closer
to 2.79 default lighting.
Also the requirement is that the lighting needs to be ok with
all material parameter ranges so this is the best we can do.
Viewport: Change default roughness to 0.4
This is in order to match the previous default matcap better.