v5.0.0

CHANGES:

• Do not zero out the non-prefix-length part of the address in
  {V4,V6}.Prefix.t (#99 @hannesm)
  Removed {V4,V6}.Prefix.of_address_string{,_exn} and
  {V4,V6}.Prefix.to_address_{string.buffer}

  To port code:

  • if you rely on Prefix.of_string to zero out the non-prefix-length address
    bits, call Prefix.prefix : t -> t subsequently.
  • Prefix.of_address_string{,_exn} can be replaced by
    Prefix.of_string{,_exn}, to retrieve the address use
    Prefix.address : t -> addr.
  • The Prefix.to_address_{string,buffer} can be replaced by
    Prefix.to_{string,buffer}, where Prefix.t already contains the IP
    address to be printed.
  • Instead of passing {V4,V6}.t * {V4,V6}.Prefix.t for an
    address and subnet configuration, {V4,V6}.Prefix.t is sufficient.

• Implement {V4,V6,}.succ, {V4,V6,}.pred, {V4,V6}.Prefix.first, and
  {V4,V6}.Prefix.last functions (#94 @NightBlues)

• Rename Prefix.of_netmask to Prefix.of_netmask_exn with labelled
  arguments (~netmask and ~address), provide Prefix.of_netmask which returns
  a (t, [> `Msg of string ]) result value (#95 @hannesm)

• Fix undefined behaviour of V4.Prefix.mem with a CIDR with prefix length 0
  (#98 @verbosemode)

• Use stdlib-shims to prevent deprecation warnings on OCaml 4.08
  (@avsm)

• Remove unnecessary "sexplib0" dependency (#95 @hannesm)

• Remove "{build}" directive from "dune" dependency (#93 @craigfe)