Introduce a close callback for sessions to handle cleanup on disconne…

…ctio

Add new client-side attribute 'maxReconnectAttempts' to represent the…

… max reconnect attempts in maintaining the tcp connetion pool size, the default value is setted to 100

add read lock for websocket recv

sync with apache/dubbo-getty v1.4.12

bugfix: closing websocket connection returns invalid status code

fix wrong tls config dir path

move out task pool from session

Add: apl v2 license header

Fix: Send multiple pkgs repetitive by tcp(issue #42)

Add: listen on random port