This adds an option to the Multires modifier to sculpt directly on the
base mesh while previewing the displacement of a higher subdivisions
level. What this does it considering Multires as a regular modifier
without exposing the grid displacement to sculpt mode.
This allows to see the propagation happening in real time, which enables
to use complex tools like Cloth or Pose in much higher resolutions and
without surface noise and artifacts.
Reviewed By: sergey, Severin
Differential Revision: https://developer.blender.org/D8555
976f0113e0