Add multi channel support

1. Support multi-channels at on thread service.
2. Async reconnect support
3. Optimize log for cross platform
4. Optimize log for cocos2d, avoid crash
5. Optimize unpack logic
6. Avoid buffer attack
7. Integrate c-ares support, macro: _USE_ARES_LIB, default value is 0
8. Add macros to control whether use object pool, shared_ptr and enable send callback
9. Fix shutdown can't close connection.

Just a optimize version.

Don't use master, 3.0 developing is in progress.

2.3.9

1.Rename xxsocket::release to xxsocket::detach
2.Fix socket_select_interrupt socket ops error.
3.Optimize object_pool implementation.

Optimize, no need to call select, wait d is 0

Avoid uncessary socker.select call when wait duration is ZERO

Optimize select call when busy.

Optimize, Immediately, If there is still have data to read, no need t call select,
However, the connection exception will detected through do_read or do_write, but it's ok.

2.3.3.3

default

fix timer priority.

2.3.3.1

VERBOSE_LOG, fix timer process priority

2.3.3

fix compile error.

please upgrade to use this release.

2.3.2

Merge branch 'master' of https://github.com/halx99/xxsocket