Merge type traits from Trunk:
* Adds uchar16_t and uchar32_t support.
* Adds is_copy_constructible trait.

git-svn-id: http://svn.boost.org/svn/boost/branches/release@85474 b8fc166d-592f-0410-95f2-cb63ce0dd405
Worked around compilation problem with clang. Renamed parsers tests to avoid alarming Windows UAC. Fixes #9050.

git-svn-id: http://svn.boost.org/svn/boost/branches/release@85477 b8fc166d-592f-0410-95f2-cb63ce0dd405