message: Add delete message and update stream methods
diff: @@ -568,6 +568,14 @@ impl Manager {
  self.request(&subject, &req)
  }
  + /// Update a stream.
  + pub fn update_stream(
  + &self,
  + stream_config: StreamConfig,
  + ) -> io::Result<StreamInfo> {
  + self.add_stream(stream_config)
  + }
  +
  /// Query all stream names.
  pub fn stream_names<'a>(&'a self) -> PagedIterator<'a, String> {
  PagedIterator {
  @@ -619,6 +627,24 @@ impl Manager {
  self.request(&subject, b"")
  }
  + /// Delete message in a stream.
  + pub fn delete_message<S: AsRef<str>>(
  + &self,
  + stream: S,
  + sequence_number: u64,
  + ) -> io::Result<()> {
  + let stream: &str = stream.as_ref();
  + if stream.is_empty() {
  + return Err(Error::new(
  + ErrorKind::InvalidData,
  + "the stream name must not be empty",
  + ));
  + }
  + let subject = format!("$JS.API.STREAM.MSG.DELETE.{}", stream);
  + let req = format!("{{ seq: {} }}", sequence_number);
  + self.request(&subject, req.as_bytes())
  + }
  +
  /// Delete stream.
  pub fn delete_stream<S: AsRef<str>>(&self, stream: S) -> io::Result<()> {
  let stream: &str = stream.as_ref();
  