[boost] [range] new adaptor for iterating over equal_ranges

Hi Neil & others, I think it could be useful with a range adaptor of the following kind to iterate over equal_ranges in a multimap. E.g. SomeMultiMap map = ...; for( auto rng : map | boost::adaptors::equal_ranged ) for( auto iter : rng ) { // do something with the objects with equal keys } The resulting range would probably be bidirectional with value_type std::pair<boost::range_iterator<SomeMultiMap>::type,...>. Thoughts? -Thorsten