Module encode

Available on doc or test only.

encode modifications

(↑) This is derived work from the encode crate, including the following modifications:

• define a new Decodable trait.
• replace the Encoder trait by IoWrite.
• use IoError as the implicit error type.
• make Encodable::encode return the usize len.
• remove the types: FromError,InsufficientSpace.
• merge the categories of combinators and encoders.
• use the same combinators for encoding and decoding.
• rename combinators:
  • BE to CodecBe.
  • LE to CodecLe.
  • Cond to CodecIf.
  • Flags to CodecFlags
  • SizeEncoder to CodecLen.
  • LengthPrefix to CodecLenValue.
• merge Iter and Separated into CodecJoin, with an optional separator.
• make EncodableSize::encoded_size be a provided method.
• make CodecLenValue accept a codec for the length.
• make doc tests work with not(alloc) as well.
• support [i|u]size for Codec[Be|Le.
• remove Encodable impl for Result.
• remove all unnecessary dependencies.
• refactor macros and implementations.
• explain purity as non-mandatory.
• make combinators must_use.
• make FmtAdapter inline.
• make constructors const.