Add utility and shared_from to README

README.md

@@ -35,6 +35,7 @@ In the list below each library shows its minimum supported C++ standard and has
  [**qalgorithm.hpp**](https://github.com/iboB/itlib/tree/master/include/itlib/qalgorithm.hpp) [![Standard](https://img.shields.io/badge/C%2B%2B-11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) | Wrappers of `<algorithm>` functions which work on entire containers for less typing in the most common use-cases.
  [**rstream.hpp**](https://github.com/iboB/itlib/tree/master/include/itlib/rstream.hpp) [![Standard](https://img.shields.io/badge/C%2B%2B-11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) | Read stream. Simple `std::istream` wrappers which don't allow seeks, allowing you to be certain that reads are sequential, and thus allow a redirect, so you can represent several streams as one.
  [**sentry.hpp**](https://github.com/iboB/itlib/tree/master/include/itlib/sentry.hpp) [![Standard](https://img.shields.io/badge/C%2B%2B-11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) [![Standard](https://img.shields.io/badge/C%2B%2B-17-red.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) | A sentry class which executes a function object on destruction. Works with C++11, but it's slightly easier to use with C++17.
+ [**shared_from.hpp**](https://github.com/iboB/itlib/tree/master/include/itlib/shared_from.hpp) [![Standard](https://img.shields.io/badge/C%2B%2B-11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) | A helper class to replace `std::enable_shared_from_this` providing a more powerful interface. Similar to `enable_shared_from` from [Boost.SmartPtr](https://www.boost.org/doc/libs/1_75_0/libs/smart_ptr/doc/html/smart_ptr.html#enable_shared_from)
  [**small_vector.hpp**](https://github.com/iboB/itlib/tree/master/include/itlib/small_vector.hpp) [![Standard](https://img.shields.io/badge/C%2B%2B-11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) | A mix between `std::vector` and `itlib::static_vector`. It's a dynamic array, optimized for use when the number of elements is small. Like `static_vector` is has a static buffer with a given capacity, but can fall back to dynamically allocated memory, should the size exceed it. Similar to [`boost::small_vector`](http://www.boost.org/doc/libs/1_61_0/doc/html/boost/container/small_vector.html)
  [**span.hpp**](https://github.com/iboB/itlib/tree/master/include/itlib/span.hpp) [![Standard](https://img.shields.io/badge/C%2B%2B-11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) | A C++11 implementation of C++20's `std::span`
  [**static_vector.hpp**](https://github.com/iboB/itlib/tree/master/include/itlib/static_vector.hpp) [![Standard](https://img.shields.io/badge/C%2B%2B-11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) | A mix between `std::vector` and `std::array`: A dynamically sized container with fixed capacity (supplied as a template parameter). This allows you to have dynamically sized vectors on the stack or as cache-local value members, as long as you know a big enough capacity beforehand. Similar to [`boost::static_vector`](http://www.boost.org/doc/libs/1_61_0/doc/html/boost/container/static_vector.html).
@@ -43,6 +44,7 @@ In the list below each library shows its minimum supported C++ standard and has
  [**time_t.hpp**](https://github.com/iboB/itlib/tree/master/include/itlib/time_t.hpp) [![Standard](https://img.shields.io/badge/C%2B%2B-11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) | A thin wrapper of `std::time_t` which provides thread safe `std::tm` getters and type-safe (`std::chrono::duration`-based) arithmetic
  [**type_traits.hpp**](https://github.com/iboB/itlib/tree/master/include/itlib/type_traits.hpp) [![Standard](https://img.shields.io/badge/C%2B%2B-11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) [![Standard](https://img.shields.io/badge/C%2B%2B-17-red.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization)  | Additional type traits to extend the standard library's `<type_traits>`
  [**ufunction.hpp**](https://github.com/iboB/itlib/tree/master/include/itlib/ufunction.hpp) [![Standard](https://img.shields.io/badge/C%2B%2B-11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) [![Standard](https://img.shields.io/badge/C%2B%2B-14-yellow.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) | Unique function. A replacement of `std::function` which is non-copyable (can capture non-copyable values, and wrap non-copyable objects), and noexcept move-constructible (won't implicitly make owners no-noexcept move-constructible)
+  [**utility.hpp**](https://github.com/iboB/itlib/tree/master/include/itlib/utility.hpp) [![Standard](https://img.shields.io/badge/C%2B%2B-11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) | Several generally unrelated utility functions and helpers
 
 ## Usage