Support new CANPacket format sent over USB to the panda

[incognitojam]

Need to add support for new format in latest panda firmwares. Do we need to retain support for old firmwares? Or just introduce a breaking change and update version number accordingly.

Relevant PRs:
commaai/panda#739

[gregjhogan]

We only need to support the new format. An old version of this library can be used for the old format.

[gregjhogan]

You can query the CAN packet version:
https://github.com/commaai/panda/blob/f5857bc8fd3e1d2c27df342df85e202c7e844911/python/__init__.py#L405-L412
and raise an error if it is not the correct version:
https://github.com/commaai/panda/blob/f5857bc8fd3e1d2c27df342df85e202c7e844911/python/__init__.py#L110-L113