This is a new implementation of the mask extract operator, different from the one in the sculpt branch. I'm uploading this now because it does not depend on any changes in sculpt mode, so it can be merged independently.
The operator works, but it is not finished. For this to be useful, I need to run several BMesh operators on top of the resulting mesh to create the external loop and smooth the extracted surface. It should do the following steps:
-Extrude the external loop
- Smooth the vertices in two separate sets
- Shrinkwrap the result to the original mesh
- Extrude (as another operation adjustable in the redo panel or with the solidify modifier)
I'm also not sure if this operator belongs to object_edit as it needs to make mesh editing operations.