shared_container_iterator now uses std::shared_ptr to store the reference
to the container. boost::shared_ptr is still supported and is wrapped
into std::shared_ptr on construction, so there is overhead due to allocation
of std::shared_ptr state. Going forward, std::shared_ptr is expected
to be the primary use case. As a bonus, this eliminates the dependency
on Boost.SmartPtr.
Moved shared_container_iterator.hpp into the iterator directory and left
a forwarding header for backward compatibility.
generator_iterator now uses decltype approach to deduce value and reference
types instead of the legacy result_type typedef, which was required to be
defined by the generator function.
The default constructor of generator_iterator now value initializes its
data members to avoid using uninitialized data.
The new min_category is similar to minimum_category but accepts variable
number of iterator categories on input instead of just two, and also does
not depend on Boost.MPL for lambda placeholders. The existing minimum_category
trait has been reimplemented in terms of min_category and deprecated.
We don't yet emit deprecation warnings as there is still code that uses
the old trait which we first need to update. Eventually, minimum_category
will emit warnings and will be removed.
