Fix unindenting trailing spaces in code blocks.

git-svn-id: http://svn.boost.org/svn/boost/trunk@84187 b8fc166d-592f-0410-95f2-cb63ce0dd405
Cleaner unindentation code.

git-svn-id: http://svn.boost.org/svn/boost/trunk@84188 b8fc166d-592f-0410-95f2-cb63ce0dd405