Asynchronous tcpclient based on aqueue actor.

DEMO URL:

examples echo:

```rust

![feature(async_closure)]

use tcpclient::{TcpClient,SocketClientTrait}; use tokio::io::AsyncReadExt; use std::error::Error; use log::LevelFilter;

[tokio::main]

async fn main()->Result<(),Box> { // set logger out envlogger::Builder::new().filterlevel(LevelFilter::Debug).init();

// connect echo server
let client =
    TcpClient::connect("127.0.0.1:5555", async move |_, client, mut reader| {
        // read buff from target server
        let mut buff=[0;7];
        while let Ok(len) = reader.read_exact(&mut buff).await {
            // send buff to target server
            println!("{}",std::str::from_utf8(&buff[..len])?);
            client.send(&buff[..len]).await?;
        }
        // return true need disconnect,false not disconnect
        // if true and the current state is disconnected, it will be ignored.
        Ok(true)
    }, ()).await?;

// connect ok send buff to target server
client.send(b"1234567").await?;

// test disconnect readline 
let mut str = "".into();
std::io::stdin().read_line(&mut str)?;

// disconnect target server
client.disconnect().await?;
// wait env logger out show
std::io::stdin().read_line(&mut str)?;
Ok(())

} ```