v0.1004.0

v0.1004.0

Breaking changes

• The "encoder" attribute for message & oneof fields is now "encoding". This
  reads better and makes more sense, better to do it now.
• Conversion to & from u32 now uses the Enumeration trait rather than
  Into<u32> and TryFrom<u32>.
• The "opaque" types, bilrost::encoding::opaque::{OpaqueMessage, OpaqueValue}
  now use Cow under the hood instead of Vec, allowing them to hold borrowed
  data rather than only owned.

New features

• There is now an Enumeration trait for converting to & from u32 from
  derived enumerations.

Fixes

• Fixed some incorrect documentation.

Cleanups

• Large refactor that changes the underlying Encoder traits from
  impl Encoder<Value> for Encoding to impl Encoder<Encoding> for Value. This
  avoids issues with a new "non_local_definitions" lint which fires when trait
  implementations are derived for a function-local type.