Concept check should be performed.

  rel to: 5f2560f753e3fa72e15be386421e5d7d16864b96
  see also: https://svn.boost.org/trac/boost/ticket/9851

Signed-off-by: Kohei Takahashi <flast@flast.jp>
Adjust to new boost::iterators namespace.

Signed-off-by: Kohei Takahashi <flast@flast.jp>