[fixed] If save a file in Sculpt mode,geometry state rollback.

[tkbd]

I encountered a problem when trying the sculpting function...
How to recreate the problem?

1. Editing a file in unsaved state (See title bar of Wings3D, with "*" mark last of the filename).
   
2. Entered Sculpt mode and Do some push/pull operations.
   
3. Save the file.
   
4. Rollback to the Geometry state which before of enter Sculpt mode.
   

Currently to avoid the problem,don't save a file while editing in sculpt mode.
Also Save a file when after Sculpt mode quit.

Wings3D 2.1.5
MacOSX 10.11.6