Add Better Reflection to Code Analysis section

README.md

 *Libraries and tools for analysing, parsing and manipulating codebases.*
 
 * [Athletic](https://github.com/polyfractal/athletic) - An annotation based benchmark framework.
+* [Better Reflection](https://github.com/Roave/BetterReflection) - AST-based reflection library that allows analysis and manipulation of code
 * [Code Climate](https://codeclimate.com) - An automated code review.
 * [Dissect](https://github.com/jakubledl/dissect) - A set of tools for lexical and syntactical analysis.
 * [Exakat](https://github.com/exakat/exakat) - A static analysis engine for PHP.