Implement syncPushMsg function. Send properly shutdown to all connected agents.
Do not use message queue in connection implementation.
Fixed: Avoid pushing  or reading any protocol messages before connection is made. Since we have an async connection it can be the case that the connection is not yet succeeded, but we already starting to send messages.
Fixed: Suppress the "warning: 'register' storage class specifier is deprecated [-Wdeprecated-register]" warning.