v0.1006.0

v0.1006.0

Breaking changes

• The (unstable) internal encoding traits continue to evolve, now varying the
  implementation of TagMeasurer and moving the "allow empty" argument of
  distinguished value decoding into a const generic param.

New features

• Hash maps and hash sets can now have any kind of hasher, as long as the
  BuildHasher implements Default.
• Plain tuples can now be encoded as message fields! Tuples encode exactly the
  same as messages with field tags 0 through N-1, but the encoding of each field
  in the tuple can be specified. See the readme for more information.
• Fixed-size arrays ([T; N]) can now also be encoded as message fields. Arrays
  encode exactly the same as a collection like Vec would, except if each value
  in the array is empty the whole array is considered empty. When decoding an
  array, if a nonzero number of items is present and it is not the same number
  of items as the size of the array, the value and message being decoded are
  considered to be invalid.
• A couple third-party alternative types for Vec that have bounded size and
  inline-only storage (ArrayVec from the arrayvec and tinyvec crates) have
  been added.
• Third-party alternative types for Vec now also work with u8 items and the
  plainbytes encoding.

Fixes

• Added a Self: Default bound to the impl for Message when there are ignored
  fields. This means that it can be possible to have a message type with ignored
  fields and generically typed fields that don't implement Default; rather
  than failing to compile, it will now simply not implement Message.

Cleanups

• Consolidated (almost) all the standard impls of the EmptyState trait into
  the same module.