context: merge from trunk


git-svn-id: http://svn.boost.org/svn/boost/branches/release@84673 b8fc166d-592f-0410-95f2-cb63ce0dd405
Merged changes from trunk. Fixes operator<< handling of width specification.

git-svn-id: http://svn.boost.org/svn/boost/branches/release@84674 b8fc166d-592f-0410-95f2-cb63ce0dd405
Merged changes from trunk. Fixes #8614.

git-svn-id: http://svn.boost.org/svn/boost/branches/release@84677 b8fc166d-592f-0410-95f2-cb63ce0dd405