API Proposal: Check Disposed Socket

[erictuvesson]

Justification

It would be nice if there was a way to check if a socket is disposed.
Right now I suppose I can check on IsConnected and if connect I expect it is not disposed.

https://github.com/chronoxor/NetCoreServer/blob/master/source/NetCoreServer/TcpSession.cs#L177-L195

API Proposal

Having a boolean property to just check IsDisposed or IsSocketDisposed or just a wrapper over socket, just to give a easy to understand property saying that it is disposed.

[chronoxor]

Add into release 3.0.8