RapidXML download URL is dead

```
          --- LOG END ---
          error: downloading 'https://kumisystems.dl.sourceforge.net/project/rapidxml/rapidxml/rapidxml%201.13/rapidxml-1.13.zip' failed
          status_code: 6
          status_string: "Could not resolve hostname"
          log:
          --- LOG BEGIN ---
          Could not resolve host: kumisystems.dl.sourceforge.net
```