DPKT 1.9.3 release
- drop python 2.6 support
- add python 3.7, 3.8 support
- fix netbios name encoding and decoding
- properly set type of last vlan tag to type of eth.data layer
- fix QinQ vlan tag parsing with miscellaneous data
- add explicit iter to dpkt.Packet so dict() maps the fields nicely
- fix ipv6 packet so that it can be used for generating IPv6 data
- handle zero Eth type
- python 3 compatibility fixes