Moved from `io::Write` to `bytes::BufMut`, etc.
TODO: Move from `io::Read` to `bytes::Buf` (SerializedMessage::<impl MessageValue>::from_buffer(impl Buf))
Fortune for rsh's current commit: Future small blessing − 末小吉
Untyped serialized mmessages cannot be deserialized, they must first be given a type with `into_typed<V>()`. This operation is unsafe as it may cause a potential type confusion if the message"s original `V` is different from the newly specified `V`.
Fortune for rsh's current commit: Half curse − 半凶
When implementing tests for signing and/or encrypting messages, we can just implement the `MessageSender`/`MessageReceiver` traits when needed then call into this function.
(Those traits may need refactoring if the format of the adapter is not desireable (i.e. `&self` instead of `&mut self` or `self`; we could only blanket-impl those function to `Fn()` closures, not `FnMut()` or `FnOnce()`. (not that we should try this.)), but for now we"ll leave it as it is.)
Fortune for rsh's current commit: Small blessing − 小吉
Avril