[boost] [iterator] Move iterators to a separate namespace

Subject: [boost] [iterator] Move iterators to a separate namespace
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2014-07-05 15:49:44

Hi,

I've created this pull request a few days ago:

https://github.com/boostorg/iterator/pull/5

It basically moves all iterators to boost::iterators namespace (while still 
importing the symbols to boost namespace for backward compatibility). This 
change is also intended to fix the counting_iterator_test test on older 
compilers, which was broken by my previous pull request (there appeared a name 
clash with Boost.TypeTraits). Could it be merged?