fix possible crash when reverting a document

src/App/Document.cpp

@@ -1755,6 +1755,7 @@ void Document::restore (void)
         signalTransactionRemove(*(*obj), 0);
     }
     for (std::vector<DocumentObject*>::iterator obj = d->objectArray.begin(); obj != d->objectArray.end(); ++obj) {
+        (*obj)->setStatus(ObjectStatus::Destroy, true);
         delete *obj;
     }
     d->objectArray.clear();