Feature request: Add support for TLS

[Blaž Dular]

It would be nice to have the TLS support for the TCP server to securely communicate between server and a client.

[luolin]

https://github.com/lesismal/nbio， 这哥们儿的思路 是将net.conn的fd dup一个新的fd，然后加到事件循环中，这样就可以复用tls的read和write了。