Blender Git Loki

Sculpt: Use cursor depth in trimming gestures

This adds an operator property to use the paint cursor radius and
position for the depth of the trimming shape created by the trimming
tools.
When enabled, the shape is located in the surface point when the gesture
started and it will have the depth of the cursor radius. When the cursor
is not over the mesh, the shape will be positioned at the center of the
depth of the whole object from the viewport camera.

Reviewed By: dbystedt, sergey

Differential Revision: https://developer.blender.org/D9129