I haven't found, neither in the docs nor in the source code, any API to create groups or get the groups registered on the network. It is possible to get the `ZWaveGroup` objects from the `groups` property of `ZWaveNode`, add and remove nodes, change group attributes etc., but there's no equivalent for groups to e.g. `ZWaveNetwork.create_scene` or `ZWaveNetwork.get_scenes`. Is this intentional, a lacking feature, or am I missing something?