- use `max_items` in `getItems` calls for bundles, as otherwise some pubsub service may
return full nodes, which may be huge is `max_items=1` is not set on the node, possibly
resulting in timeouts.
- the plugin was crashing when TWOMEMO devices list node has no items at all. This is not
the case anymore.
- a naive parsing method has been implemented in `xml_tools` to replace the
serialisation/deserialisation method. This should be more efficient and will avoid
annoying `ns0:` prefixes in XML logs.