message: Mark file as modified after purging deleted translations
  Fixes
diff: @@ -2662,6 +2662,8 @@ void PoeditFrame::OnPurgeDeleted(wxCommandEvent& WXUNUSED(event))
  dlg->ShowWindowModalThenDo([this,dlg](int retcode){
  if (retcode == wxID_YES) {
  m_catalog->RemoveDeletedItems();
  + m_modified = true;
  + UpdateTitle();
  UpdateMenu();
  }
  });
  