Discuss C++ Allocators

Ever wanted to use your own memory allocator with standard C++ library components? Ever wanted to track memory usage by class or instance? This will be an online introduction to "stateless" and "stateful" allocators in C++17 and newer followed by open discussion, questions, and answers.

From [cppreference.com](https://en.cppreference.com/w/cpp/named_req/Allocator):
"Every standard library component that may need to allocate or release storage, from std::string, std::vector, and every container except std::array, to std::shared_ptr and std::function (until C++17), does so through an Allocator". For general background info, see https://en.cppreference.com/w/cpp/named_req/Allocator.

Attendees will want to already have at least a basic understanding of what class templates are in C++.