UnitySocketIO using websocket-sharp instead of WebSocket4Net

• UnitySocketIO is the only usable socket.io client for unity3d, but it's using WebSocket4Net and SuperSocket.ClientEngine as underlying libraries, which are somewhat buggy and unstable.
• There are times when the MessageReceived event handler is not called, even though the client has received a message packet from the server, and the message silently gets dropped.
• When WebSocket4Net library used by UnitySocketIO was replaced with websocket-sharp, the problem has been solved.
• SimpleJson library used by UnitySocketIO was updated to the latest version (v0.30.0), because the old one caused crashes in some cases.

###How to use###

Copy all the DLLs from /SocketIO/bin/Debug/ to any folder of your project (e.g. Assets/Plugins/SocketIO/)

###Avoiding too long wait on Close event###

websocket-sharp uses AutoResetEvent.WaitOne on Close event, but it looks like socket.io server doesn't return Close frame and the client must wait until the timeout (5 seconds) expires.

If you add just one line below in the method "private bool close (byte [] frameAsBytes, int timeOut, Func release)" of "websocket-sharp/WebSocket.cs" file, it'll be solved.

private bool close (byte [] frameAsBytes, int timeOut, Func<bool> release)
{
  timeOut = 0; // no closing handshake
  
  var sent = frameAsBytes != null && _stream.Write (frameAsBytes);
  ...

If you want to build this library for iOS devices, you have to copy all the sources of SimpleJson, websocket-sharp, UnitySocketIO-WebSocketSharp to a folder of your project, instead of the DLLs.

• And before you build it, you have to modify WebSocket.cs of websocket-sharp as follows:

internal delegate bool SendBytesFunc (Opcode opcode, byte [] data);
internal delegate bool SendStreamFunc (Opcode opcode, Stream stream);

private void send (Opcode opcode, byte [] data, Action<bool> completed)
{
  //Func<Opcode, byte [], bool> sender = send;
  SendBytesFunc sender = send;
  ...
}

private void send (Opcode opcode, Stream stream, Action<bool> completed)
{
  //Func<Opcode, Stream, bool> sender = send;
  SendStreamFunc sender = send;
  ...
}

• Modify Net/ListenerAsyncResult.cs of websocket-sharp as follows:

internal void Complete (Exception exc)
{
  ...
  //ThreadPool.UnsafeQueueUserWorkItem (InvokeCB, this);
  ThreadPool.QueueUserWorkItem (InvokeCB, this);
}

...

internal void Complete (HttpListenerContext context, bool synch)
{
  ...
  //ThreadPool.UnsafeQueueUserWorkItem (InvokeCB, this);
  ThreadPool.QueueUserWorkItem (InvokeCB, this);
}

• Uncomment "#define SIMPLE_JSON_NO_LINQ_EXPRESSION" in SimpleJson.cs.

##License (The MIT License)

Copyright (c) 2014 kaistseo and other contributors

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.