:mod:`cpp-netlib` 0.9

* **IMPORTANT BREAKING CHANGE**: By default all compile-time heavy parser

implementations are now compiled to external static libraries. In order to use

:mod:`cpp-netlib` in header-only mode, users must define the preprocessor

macro ``BOOST_NETWORK_NO_LIB`` before including any :mod:`cpp-netlib` header.

This breaks code that relied on the version 0.8.x line where the library is

strictly header-only.

* More consistent message API for client and server messages (request and

response objects).

* Refactoring of internal implementations to allow better separation of concerns

and more manageable coding/documentation.

* Client and Server constructors that support Boost.Parameter named parameters.

* Client and Server cosntructors now take in an optional reference to a Boost.Asio

``io_service`` to use internally.

* Documentation updates to reflect new APIs.