The ssl_stream wrapper provides C++11 move semantics for ssl::stream,
as well as incorporating the flat_stream workaround for a performance
problem with ssl::stream writes and buffer sequences having length
greater than one.
fix#575, fix#604, fix#608, fix#634, fix#712
All examples are rewritten:
* Using Best Practices
* Mostly self-contained
* New examples to complete the feature matrix
* The server-framework example is removed