3.0.0

CHANGES:

• Include Mirage_protocols.ETHERNET module type in ethernet directly, remove
  dependency on mirage-protocols (#8 @hannesm)
• The ethernet library is now wrapped, this means a lot of API breakage.
  The most used binding, Ethernet_wire.sizeof_ethernet is now known as
  Ethernet.Packet.sizeof_ethernet. (#8 @hannesm)