BIM: Fix IFC type assignment not being saved to file

As the title says, this is simple fix - basically right now anytime user
changed Link property to point to proper IFC type, we weren't writing to
the IFC file buffer to finally write it to the file if user would save
it.

So this patch makes sure we write to this buffer by calling appropriate
function, and making ifc object have proper pointer to IFC type.

src/Mod/BIM/nativeifc/ifc_objects.py

@@ -65,6 +65,7 @@ class ifc_object:
         elif prop == "Schema":
             self.edit_schema(obj, obj.Schema)
         elif prop == "Type":
+            self.edit_type(obj)
             self.assign_classification(obj)
         elif prop == "Classification":
             self.edit_classification(obj)