Support asio 1.11.x

Sync doc.
Version number keeps unchanged.

Support heartbeat (via OOB data), see ASCS_HEARTBEAT_INTERVAL macro for more details.
Support scatter-gather buffers when receiving messages, this feature needs modification of i_unpacker, you must explicitly define
 ASCS_SCATTERED_RECV_BUFFER macro to open it, this is just for compatibility.
Simplify lock-free mechanism and use std::atomic_flag instead of std::atomic_size_t.
Optimize container insertion (use series of emplace functions instead).
Demo echo_client support alterable number of sending thread (before, it's a hard code 16).
Fix bug: In extreme cases, messages may get starved in receive buffer and will not be dispatched until arrival of next message.
Fix bug: In extreme cases, messages may get starved in send buffer and will not be sent until arrival of next message.
Fix bug: Sometimes, connector_base cannot reconnect to the server after link broken.

known issues:
1. heartbeat mechanism cannot work properly between windows (at least win-10) and Ubuntu (at least Ubuntu-16.04).

Drop unnecessary macro definition (ASIO_HAS_STD_CHRONO).
Simplify header files' dependence.
Add Visual C++ solution and project files (Visuall C++ 14.0).
Monitor time consumptions for message packing and unpacking.
Fix bug: pop_first_pending_send_msg and pop_first_pending_recv_msg cannot work.

Introduce lock-free mechanism for some appropriate logics (many requesters, only one can succeed, others will fail rather than wait).
Remove all mutex (except mutex in object_pool, service_pump, lock_queue and udp::socket).
Sharply simplified timer class.

Fix bug: ascs::list cannot be moved properly via moving constructor.
Use ASCS_DELAY_CLOSE instead of ASCS_ENHANCED_STABILITY macro to control delay close duration,
 0 is an equivalent of defining ASCS_ENHANCED_STABILITY, other values keep the same meanings as before.
Move ascs::socket::closing related logic to ascs::object.
Make ascs::socket::id(uint_fast64_t) private to avoid changing IDs by users.
Call close at the end of shutdown function, just for safety.
Add move capture in lambda.
Optimize lambda expressions.

Support non-lock queue, it's totally not thread safe and lock-free, it can improve IO throughput with particular business.
Demonstrate how and when to use non-lock queue as the input and output message buffer.
Queues (and their internal containers) used as input and output message buffer are now configurable (by macros or template arguments).
New macros--ASCS_INPUT_QUEUE, ASCS_INPUT_CONTAINER, ASCS_OUTPUT_QUEUE and ASCS_OUTPUT_CONTAINER.
Drop macro ASCS_USE_CONCURRENT_QUEUE, rename macro ASCS_USE_CONCURRE to ASCS_HAS_CONCURRENT_QUEUE.
In contrast to non_lock_queue, split message_queue into lock_queue and lock_free_queue.
Move container related classes and functions from st_asio_wrapper_base.h to st_asio_wrapper_container.h.
Improve efficiency in scenarios of low throughput like pingpong test.
Replaceable packer/unpacker now support replaceable_buffer (an alias of auto_buffer) and shared_buffer to be their message type.
Move class statistic and obj_with_begin_time out of ascs::socket to reduce template tiers.

Support concurrent queue (https://github.com/cameron314/concurrentqueue), it's lock-free.
Optimize locks on msg sending and dispatching.
Drop original congestion control and add a semi-automatic congestion control.
Drop post_msg_buffer and corresponding functions (like post_msg()), timer (ascs::socket::TIMER_HANDLE_POST_BUFFER).

Optimize locks on msg sending and dispatching.
Drop original congestion control and add a semi-automatic congestion control.
Drop post_msg_buffer and corresponding functions (like post_msg()), timer (ascs::socket::TIMER_HANDLE_POST_BUFFER).

ext directory refactoring.
Add ascs::ext::tcp, ascs::ext::udp and ascs::ext::ssl name spaces.
Make timer_info's member variables mutable (except the id), so we can change them in std::set.
Make shutdown operation thread safe.
Drop macro ASCS_OBSOLETED_OBJECT_LIFE_TIME and ASCS_THIS, and ssize_t definition for Visual C++.
Fix bug: repeatedly join the same service thread while stopping service_pump if you restarted it.
Version number keeps unchanged.

Re-base onto st_asio_wrapper 1.2.0
Add class std_list(a substitute of std::list before gcc 5.1), whose size() function has O(1) complexity.

Strip boost (Based on st_asio_wrapper 1.1.3).
Need c++14, if your compiler detected duplicated 'shared_mutex' definition, please define ASCS_HAS_STD_SHARED_MUTEX macro.
Need to define ASIO_STANDALONE and ASIO_HAS_STD_CHRONO macros.
Collect all macros together.