[Bf-committers] Sculpt smooth brush ignores hidden geometry

[Erik Sejersen]

Noticed the smooth brush ignores hidden parts of the mesh when using
multires but not regular mesh or dynamic topology.
In my attempts to find a solution I wasn't able to find a way to check to
see if the vertices are hidden as the code cannot access the internals of
the struct PBVH.

Creating a PBVHVertexIter gives access to grid_hidden but seems wrong to
create it without using it properly.

-Erik