Open addressing hash table on C++

Hope see here full-featured C++-container implementing fast and compact open addressing hash table on C++.

Proof-of-concept (see benchmark.cpp) shows that such map can be 3x faster than std::unordered_map.

API should be very like to std::unordered_map, so approximate roadmap is:

1. One more template type parameter class Pred = std::equal_to<Key>
2. Member function at
3. Member function clear
4. Member function empty
5. Member function insert
6. Member function equal_range
7. Member function swap
8. Member function operator=
9. Member functions load_factor, max_load_factor, rehash, reserve
10. Constant members
11. Member types: difference_type, hasher, key_type, mapped_type, reference, size_type, value_type, pointer, const_reference, key_equal
12. Iterators: member types iterator, const_iterator, member functions begin, end, cbegin, cend
13. Member function emplace
14. Member function emplace_hint
15. Relational operators
16. Non-member function overload: swap
17. Move semantics