Update handling of entity_instance GlobalId Issue #18

Author: DimitriosThe

mvd.py

@@ -204,7 +204,10 @@ def correct_for_export(all_data):
                     d[k] = 0
 
             elif isinstance(v, ifcopenshell.entity_instance):
-                d[k] = v[0]
+                if g := getattr(v, 'GlobalId', None):
+                    d[k] = g
+                else:
+                    d[k] = str(v)
     return all_data