Enable MSVC extensions. /Za is buggy and unrecommended. It breaks rvalue references in newer MSVC compilers.
Copyright updates.
Added class unique_ptr under boost::movelib namespace. This could be lifted to ::boost namespace if the community agrees.

This unique_ptr implementation is based on C++14, including make_unique functions. Large parte of the testsuite is based on Howard Hinnant's unique_ptr emulation testsuite.
Added missing cstddef for std::nullptr_t
Added missing cstddef includes and corrected the use of plain "size_t"
Corrected typos in documentation
Merge branch 'develop'