1. Boost dependencies

Personally I found the online documentation to be unclear on this question, so
here are the facts based on the source code and the upstream build.

The source code includes headers (conditionally) from the following Boost
libraries:

Boost.Align
Boost.Array
Boost.Assert
Boost.Bind
Boost.Chrono
Boost.Config
Boost.Context
Boost.Coroutine
Boost.DateTime
Boost.Detail
Boost.Exception
Boost.Function
Boost.Limits
Boost.MakeShared
Boost.Regex
Boost.SmartPtr
Boost.ThrowException
Boost.TypeTraits
Boost.Units
Boost.Utility

Most, but not all, of the Boost dependencies have a user-visible controlling
macro, ASIO_DISABLE_BOOST_<library>.

If Asio is built in standalone mode (which is turned on automatically if a
C++11-capable compiler is detected) "most of Asio may now be used without a
dependency on Boost header files or libraries". Note that "standalone mode" is
not the same as a "non-Boost version of the library". In other words, the
non-Boost version of the library can in turn be in standalone mode.

In standalone mode most of the Boost dependencies are disabled directly via
their controlling macros (in asio/detail/config.hpp), but the following ones
are not:

Boost.Context
Boost.Coroutine
Boost.Detail
Boost.Exception
Boost.Function
Boost.SmartPtr
Boost.TypeTraits
Boost.Utility

Some of these are enabled based on platform and feature check macros. For
example, Boost.TypeTraits headers will be included if <type_traits> is not
available. Others, like Boost.Coroutine, can be controlled independently of
ASIO_STANDALONE (in this case via ASIO_DISABLE_BOOST_COROUTINE or the upstream
--enable-boost-coroutine configure option).

Currently we force the standalone mode and then disable the rest of the Boost
dependencies. Currently this is not configurable but in the future we may
change that.