Fix the following error:

```
Exception in thread Thread-4:
Traceback (most recent call last):
  File "/usr/lib/python3.7/threading.py", line 917, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.7/threading.py", line 1166, in run
    self.function(*self.args, **self.kwargs)
  File "/usr/local/lib/python3.7/dist-packages/pimdm/InterfacePIM.py", line 152, in send_hello
    self.send(packet.bytes())
  File "/usr/local/lib/python3.7/dist-packages/pimdm/InterfacePIM6.py", line 86, in send
    super().send(data=data, group_ip=group_ip)
  File "/usr/local/lib/python3.7/dist-packages/pimdm/InterfacePIM.py", line 113, in send
    if self.drop_packet_type is not None:
AttributeError: 'InterfacePim6' object has no attribute 'drop_packet_type'
```

Add command to list instances && fix issue of -mvr and -uvrf being mutually exclusive && fix state refresh deadlock && include originator state on -ls

* First try IPv6 support... based on HPIM-DM IPv6 commit

* fix membership removal of interface (IGMP/MLD)

* Add support for unicast and multicast VRFs && remove some commented code && IGMP/MLD snake case global variables

Bump setup-python from v1 to v2

Allow enabling/disabling StateRefresh on previously disabled/enabled PIM-DM interfaces without having to remove them

Pim dm implementation

react to new neighbors (resend state refresh msg/clear prune limit timer <- based on downstream/upstream neighbor) & fix originator logger & remove dead code

fix loggers (using LoggerAdapter) & added join_prune_logger in Downstream/Upstream prune state machine & added originator_logger & fix downstream/upstream state machines

fix AssertCancel message (metric) & protocol information defined before initializing sockets & use of logs for tests & routing information stored in a different way (in Kernel) & fix some state machines & fix unicast routing updates & fix delete of tree information

fix Hello&Neighbor (timers and deadlocks) & check olist of all trees when interface changes number of neighbors & packet reception handled inside of interfaces' classes (instead of methods in separate files) & fix send of state refresh through non-root interfaces (if assert loser dont check prune and assert state)