Bimap uses std::unary_function/std::binary_function which are removed in c++17

[Andy Vincent <andrew.vincent@…>]

Some code, which uses boost::bimap does not compile on Windows 10 with Visual Studio 2017 Professional using the compiler flag /std:c++latest (which enables the C++17 standard).

This is due to std::unary_function (and similar templates) being removed in C++17.

A number of structures in the underlying code of boost::bimap (e.g. bimaps::container_adaptor::detail::comparison_adaptor, bimaps::relation::support::data_extractor_implementation) derive from std::unary_function or std::binary_function.