Cut WIP: Import/Export cut information to/from .3mf file

+ Fixed a crash during change object selection, when CutGizmo is On
+ Fixed Undo/Redo (was accidentally broken with 7912613dc8)

src/libslic3r/Model.hpp

@@ -351,7 +351,7 @@ public:
     // Holes to be drilled into the object so resin can flow out
     sla::DrainHoles         sla_drain_holes;
 
-    // Connectors to be added into the object after cut
+    // Connectors to be added into the object before cut and are used to create a solid/negative volumes during a cut perform
     CutConnectors           cut_connectors;
     CutObjectBase           cut_id;