Body::reader and Body::writer meanings are reversed, for
consistency with the names of the stream operations:
* Body::reader is used for read, read_some, async_read, async_read_some
* Body::writer is used for write, write_some, async_write, async_write_some
Actions Required:
* Swap the reader and writer names for user defined Body types
* Swap use of is_body_reader and is_body_writer
* Fields::writer replaces Fields::reader
* The FieldsWriter concept is renamed from FieldsReader
Actions Required:
* Rename reader to writer for user defined Fields
Some `basic_parser` member functions are renamed:
* chunked() was is_chunked()
* upgrade() was is_upgrade()
* keep_alive() was is_keep_alive()
Actions Required:
* Rename member function invocations at call sites
* The function has_content_length_impl is added to the
requirements of Fields.
Actions Required:
* Implement has_content_length_impl for user-defined Fields
fix#769
The following classes are removed:
* handler_type
* async_result
* async_completion
* is_dynamic_buffer
* is_const_buffer_sequence
* is_mutable_buffer_sequence
* handler_alloc
Actions Required:
* Use BOOST_ASIO_HANDLER_TYPE instead of handler_type
* Use BOOST_ASIO_INITFN_RESULT_TYPE instead of async_result
* Use boost::asio::async_completion
* Use boost::asio::is_dynamic_buffer
* Use boost::asio::is_const_buffer_sequence
* Use boost::asio::is_mutable_buffer_sequence
* boost::asio::associated_allocator_t replaces handler_alloc
fix#767
The write family of HTTP stream algorithms no longer returns
error::end_of_stream when the message indicates that the connection
should be closed.
Actions Required:
* Add code to servers to close the connection after successfully
writing a message where `message::keep_alive()` would return `false`.
