Update packet handling for IPv6.  BIG caveat on mixed AFI packets, when a NAK has a different source to multicast group AFI things are rather confusing.
Update packet handling for IPv6.  BIG caveat on mixed AFI packets, when a NAK
has a different source to multicast group AFI things are rather confusing.

jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm