handle ItemsChanged signals

The previous PropertiesChanged on root implementation has been
replaced with an ItemsChanged signal that does the same job.
This time, instead of recording the message as is, we
instead unroll it. This will be compensated for during replay
in giving the user the option to replay the recording in packed
ItemsChanged signals or individual PropertiesChanged signals.

victronenergy/venus#789

dbusdevice.py

@@ -15,6 +15,9 @@ def __init__(self, bus, name, eventCallback):
 		self._dbus_conn.add_signal_receiver(self._on_dbus_value_changed,
 			dbus_interface='com.victronenergy.BusItem', signal_name='PropertiesChanged', path_keyword='path',
 			sender_keyword='service_id')
+		self._dbus_conn.add_signal_receiver(self._on_dbus_items_changed,
+			dbus_interface='com.victronenergy.BusItem',
+			signal_name='ItemsChanged', path='/', sender_keyword='service_id')
 
 	def __del__(self):
 		logger.debug('__del__ %s' % self)
@@ -26,6 +29,11 @@ def _on_dbus_value_changed(self, changes, path=None, service_id=None):
 		if service_id == self._service_id:
 			self._eventCallback(self._dbus_name, path, changes)
 
+	def _on_dbus_items_changed(self, items, service_id=None):
+		if service_id == self._service_id:
+			for path, changes in items.items():
+				self._eventCallback(self._dbus_name, path, changes)
+
 	## Returns the dbus-service-name which represents the Victron-device.
 	def __str__(self):
 		return "DbusDevice=%s" % self._dbus_name