* Add writer::prepare(msg&) interface to set Content-Type

Boost.Http
* Use enum instead of bool in isRequest

Docs:
* Include Example program listings in the docs
* Fix index in docs
* melpon sandbox?
* Implement cleanup-param to remove spaces around template arguments
  e.g. in basic_streambuf move constructor members
* Don't put using namespace at file scope in examples,
  do something like "using ba = boost::asio" instead.

Core:
* Replace Jamroot with Jamfile
* Fix bidirectional buffers iterators operator->()
* Complete allocator testing in basic_streambuf

WebSocket:
* more invokable unit test coverage
* More control over the HTTP request and response during handshakes
* optimized versions of key/masking, choose prepared_key size
* Give callers control over the http request/response used during handshake
* Investigate poor autobahn results in Debug builds
* Fall through composed operation switch cases
* Use close_code::no_code instead of close_code::none
* Make request_type, response_type public APIs,
  use in stream member function signatures

HTTP:
* Define Parser concept in HTTP
  - Need parse version of read() so caller can set parser options
    like maximum size of headers, maximum body size, etc
* add bool should_close(message_v1 const&) to replace the use
  of eof return value from write and async_write
* More fine grained parser errors
* HTTP parser size limit with test (configurable?)
* HTTP parser trailers with test
* Decode chunk encoding parameters
* URL parser, strong URL character checking in HTTP parser
* Fix prepare() calling content_length() without init()
* Complete allocator testing in basic_streambuf, basic_headers
* Custom HTTP error codes for various situations
* Branch prediction hints in parser
* Check basic_parser_v1 against rfc7230 for leading message whitespace
* Fix the order of message constructor parameters:
  body first then headers (since body is constructed with arguments more often)
* Unit tests for char tables
* Remove status_code() from API when isRequest==true, et. al.
* Permit sending trailers and parameters in chunk-encoding chunks

Future:

* SOCKS proxy client and server implementations

