rust websocket tokio server frame.

Examples Echo

```rust use anyhow::Result; use futuresutil::StreamExt; use log::*; use websocketserver_async::{Builder, IPeer, IWebSocketServer};

[tokio::main]

async fn main() -> Result<()> { envlogger::Builder::new() .filterlevel(log::LevelFilter::Debug) .init(); let websocketserver = Builder::new("0.0.0.0:8888") .setconnectevent(|addr| { info!("{} connect", addr); true }) .setinputevent(|mut reader, peer, _| async move { while let Some(msg) = reader.next().await { let msg = msg?; if msg.istext() || msg.isbinary() { peer.sendmessage(msg).await?; } } Ok(()) }) .build() .await; websocketserver.startblock(()).await?; Ok(()) }

```