dnode with websocket and reconnect

example.js

````js
var dnode = require('dnode');
var PassThrough = require('stream').PassThrough;
var inject = require('reconnect-core');

var reconnect = inject(function (_url) {
    return websocket_stream(_url);
});


var d = dnode({
    clientfn1: function(){console.log(111)}
});

/*
    define a cacheStream here
    dnode will write to this cacheStream
*/
var cacheStream = new PassThrough({
    objectMode: false,
    highWaterMark: 16384, //16k
    decodeStrings: false,
    readableObjectMode: true,
    writableObjectMode: true
});

/*
    d.pipe(cacheStream); 
    do not use pipe here, it will make stream end
*/
d.on('data', function(data) {
    cacheStream.push(data);
});


// add reconnect
var re = reconnect({}, function (ws_stream) {

    // reset dnode status，makesure it not end
    d._ended = false;
    d.writable = true;
    d.readable = true;

    /*
    dnode will write to cacheStream
    if websocket conn is lost
    data will be cached and will send after reconnect 
    */

    // cache_stream -> websocket_stream
    cacheStream.pipe(ws_stream);
    // websocket_stream -> dnode
    ws_stream.pipe(d);
    
    d.once('end', function () {
       
        // unpipe previsous streams
        ws_stream.unpipe(d);
        cacheStream.unpipe(ws_stream);

        // pause cache because websocket end
        cacheStream.pause();

        // reset dnode status，makesure it not end
        d.writable = true;
        d.readable = true;
    });
});

re.on('connect', function (con) {

    /*
        make remote events happen again
    */

    if (d.proto) {
        d.once('pipe', function () {
            d.proto.start();
            cacheStream.resume();
        });
     }

    debugSock('connect');
})

.on('reconnect', function (n, delay) {
    console.log('try reconnect');
})

.on('error', function (err) {
    console.log(err);
});

re.connect('http://xxx.xx.xx/websocket');
```