see st_asio_wrapper.h for more details.

please upgrade your monitor.

Wiped out error messages printed by st_udp_socket caused by explicit close.

Improved the performance of the default packer in compatible edition, so
i_unpacker's signature been changed.

1. st_object_pool::create_client been renamed to st_object_pool::create_object for a better readability;
2. st_ssl_object_pool::create_client been renamed to st_ssl_object_pool::create_object for the same reason;
3. add_client been removed from st_client to st_tcp_client and st_udp_client respectively because it's implementation are different on TCP and UDP;
4. if re-connecting abandoned, write info log.

added some class diagrams sequence charts.

1. force_close(false) or graceful_close(false) sometimes cannot forbid
st_socket reconnecting, especially the input TPS is hight;
2. not directly dispatch msgs in force_close any more.

wiped off the constant attribute of inner_packer and inner_unpacker to make packer and unpacker changeable, not just replaceable;
avoided resolver.resolve throw exception;
added another two types of packer and unpacker----fixed length packer and unpacker, prefix and suffix packer and unpacker.

Fix bug: reconnecting may be stopped by another reconnecting, see force_close and graceful_close for more details.

Add support for suspending msg sending in runtime.

Abstract the same logic between st_tcp_client and st_udp_client to a new
class st_client_base;
Abstract the same logic between st_tcp_socket and st_udp_socket to a new
class st_socket;
Add helper function safe_send_msg and safe_broadcast_msg;
Add support to suspend dispatching msgs in runtime.

No any material code changes.