asio C++ library

The asio 1.5.3 release continues the 1.5.x development release series. This means that subsequent 1.5.x releases may make breaking changes to the API. The changes in this release include: * Added a new, completely rewritten SSL implementation. The new implementation compiles faster, shows substantially improved performance, and supports custom memory allocation and handler invocation. It includes new API features such as certificate verification callbacks and has improved error reporting. The new implementation is source-compatible with the old for most uses. However, if necessary, the old implementation may still be used by defining `(BOOST_)ASIO_ENABLE_OLD_SSL`. * Added new `asio::buffer()` overloads for `std::array`, when available. The support is automatically enabled when compiling in -std=c++0x mode on g++ 4.3 or higher, or when using MSVC 10. The support may be explicitly enabled by defining `(BOOST_)ASIO_HAS_STD_ARRAY`, or disabled by defining `(BOOST_)ASIO_DISABLE_STD_ARRAY`. * Changed to use the C++0x standard library templates `array`, `shared_ptr`, `weak_ptr` and `atomic` when they are available, rather than the Boost equivalents. * Support for `std::error_code` and `std::system_error` is no longer enabled by default for g++ 4.5, as that compiler's standard library does not implement `std::system_error::what()` correctly.