[boost] [range] workaround metafunction<const Array> under VC7.1

Hi, If you add const-qualification to array type *by hand* when using metafunctions, VC7.1 seems to fail to order partial specialized templates. (VC8 has no problem.) For trivial example, int arr[10]; boost::begin(arr); fails under 1.34.0. He can't find partial specialization for array. I don't know what happens, but the workaround is known. That is, under VC7.1, please prefer the form typename range_metafunction<typename boost::add_const<T>::type>::type to typename range_metafunction<const T>::type everywhere T can be an array type. -- Shunsuke Sogame