CMake compatibility issues

[yissacharwe]

get this warning when configuring cmake:

CMake Deprecation Warning at CMakeLists.txt:2 (cmake_minimum_required):
Compatibility with CMake < 3.5 will be removed from a future version of
CMake.

Editing CMakeLists.txt:2 to "cmake_minimum_required(VERSION 2.8...3.5)" prevents the error message,
but the compatibility issues are not solves.

At the SFML-Game-Development-Book-master\CMake directory there is a FindSFML.cmake file,
which is said to no longer be supported anymore, but rather SFMLConfig.cmake is now used instead.