Revert "part deletion handling"

This reverts commit 6ab2002021ac1df26ebe77f488f5cd94e1df0b26.

src/App/Plane.cpp

@@ -42,10 +42,7 @@ PROPERTY_SOURCE(App::Plane, App::GeoFeature)
 Plane::Plane(void)
 {
     ADD_PROPERTY(PlaneType,(""));
-    //placement can't be changed
     Placement.StatusBits.set(3, true);
-    //plane can not be deleted by user
-    StatusBits.set(ObjectStatus::Undeletable, true);   
 
 }