FMSLogo Code

This was a regression in FMSLogo 7.0.0 by some cleanup in 3dsolid.cpp.
The fix is to redo the cleanup correctly.
It adds some code that shouldn't have been removed and removed some code that should have been.

This change was prepared by diffing the changes made in 7.0.0.
I don't have a good understanding of the code, nor do I really understand what these changes do.