This introduces two alternative subdivision modes that generates displacement on the grids that look as Simple subdivisions but while using the Catmull-Clark subdivision type in the modifier. This way, Simple and Catmull-Clark subdivision can be combined when creating new levels if needed, for example, to sculpt hard surface objects. Subdivide simple smooths the sculpted data when creating a new subdivision level. Subdivide linear also preserves the sharpness in the sculpted data. Reviewed By: sergey Differential Revision: https://developer.blender.org/D7415