Merge from trunk: added basic rvalue support and marked some functions with BOOST_NOEXCEPT (fixes #7620)

svn path=/branches/release/boost/variant/; revision=81455
Merge from trunk: merge performance tests (refs #7620)

svn path=/branches/release/libs/variant/; revision=81456
Merge variant from trunk:
 * Fix #7718 (move constructor from template type added)
 * More tests and minor bugfixes
 * Deprecated macros replaced with new ones (thanks to Marshall Clow)

svn path=/branches/release/boost/variant/; revision=81793