Merge from trunk:
* make the library work on exception-disabled environments (fixes #8717)
* fix compilation of Boost.Variants move assignment for situations when one of the variant template classes has nothrow copy constructor and throwing move constructor (fixes #8772)
* mark move constructor of variant with BOOST_NOEXCEPT_IF (refs #7911)

[SVN r85157]
Merge from trunk:
* Fix issue with const rvalue references in Boost.Variant (fixes #8988)
* Get rid of Boost.Variant hand written non-usable move emulation and use Boost.Move instead(refs #7601). This does not mean that Boost.Variant supports move emulation now, but removes duplicate/non-working code and makes sure that Boost.Variant is able to work with boost::move

[SVN r85408]
Merge from trunk:
* Add some merge infos
* Fix unreachable code warning (fixes #8665)

[SVN r85882]