Reflection: Add visit_struct (fix fffaraz#779)

Author: myd7349

README.md

@@ -673,6 +673,7 @@ A curated list of awesome C++ (or C) frameworks, libraries, resources, and shiny
 * [Nameof](https://github.com/Neargye/nameof) - Header-only C++17 library provides nameof macros and functions to obtain the simple name of variable, type, function, macro, and enum. [MIT]
 * [Ponder](https://github.com/billyquith/ponder) - A C++11 library for reflection. [MIT]
 * [RTTR](https://github.com/rttrorg/rttr) - A C++11 library for reflection. [MIT] [website](http://www.rttr.org)
+* [visit_struct](https://github.com/cbeck88/visit_struct) - A miniature library for struct-field reflection in C++. [BSL-1.0]
 
 ## Regular Expression