[boost] cross_iterator

Hi folks, A cross_iterator is to a zip_iterator as a cross_product is to a dot_product. For example, given two sequences { a, b }, { 1, 2 }, the sequence of tuples generated by a cross_iterator would be { ( a, 1 ), ( b, 1 ), ( a, 2 ), ( b, 2 ) }. I've put my implementation of cross_iterator in the sandbox (cross_iterator.zip @ http://boost-sandbox.sourceforge.net/vault/). There's no documentation yet, but I've included a sample file that demonstrates how to use the new iterator. Please take a look and let me know what you think. Alex