Shrinking fillet surfaces

@pascal, So I just tried “TestRefitTrim” in the V7 WIP and that is a very, very useful command. I use the following technique a lot and at first glance, it seems to be automated in a 1 button operation. Very exciting.

Manual approach
-Trim 4-sided single-span surface.
-Duplicate trimmed edges
-Rebuild curves as needed to single span
-Use EdgeSrf to create new single-span surface