add /WX mscv compiler option for only mscv compiler

clang on windows support both gcc and mscv style options. Clang.exe on windows
defaults to gcc style, which will result in /WX unknown compiler command.
This will set /WX if and only if the compiler is MSVC and greater than version 1900

yaourt is outdated and insecure, use yay in README.md

Not maintained anymore: https://archlinux.fr/yaourt-en
Alternatively: spdlog is now apart of the community repo (https://www.archlinux.org/packages/community/x86_64/spdlog/)

Fix a build issue when SPDLOG_PREVENT_CHILD_FD is defined

* Ref 033fe9f1

Support for precompiled headers with SPDLOG_ENABLE_PCH

Compilation is shorten by 2 on windows with msvc. Some improvement for gcc and appleclang. Add SPDLOG_ENABLE_PCH option to CMake that is defaulted to ON. This will enable precompiled header by default if supported. It can be disable if user have a conflict of any kind. Or to check that project is still compiling with CMake version that do not support precompiled header.

Fix Windows setenv check

README: add conda as a supported package manager