Add world class, game world will managed by World.
* Add WorldSocket class, now sockets will managed by SocketEventHanlder.
* Update Game and SHSocket class, socket will auto removed when Disconnect called.
* Now we can use WorldSession::KickPlayer() to kick player.
* Player will auto kicked when he try to connect server with the same account.

Signed-off-by: Y.Moon <chglove@live.cn>