std::iterator and iterator tags. Kindaish
Functional header with std::hash<> and std::equal_to<>, as well as overloads for uint32_t and uint16_t
hash_map implementation which is kind of like std::unordered_map, but not really.
std::hash_map<>::iterator is now a forward iterator and std::hash_map<> got a begin() method to allow iteration over the set.