Improvement for Docker run C++ applications with g3log 

* This addresses the case when a PID1 process crashes and the signal handling, goes into multiple or even infinite loops due to subsequent crashes. The PR makes sure to restore all signal handlers to the original signal handling after the first crash is detected. For

Usage of C++20's new constexpr functionalities for easier usage of custom LEVELS!

Modified:
* With C++20 LEVELS's constructor can have a constexpr specifier
* const LEVELS can be replaced to be constexpr's instead

Small changes, essentially cleanup, with no actual code logic change. 
* Ensure symbol_buffer aligned same as SYMBOL_INFO
* Use constexpr for compile-time constant
* Use = default for ctor bodies to allow compiler optimize them
* Pass string by reference to prevent copying, other smaller types we can  avoid passing by reference as the type is cheaper to copy.

* trying out codespaces

* adding example vs code launch file

*  clang format configuration file replaces sublime Astyleformatter
* instructions added to pull request template
* code base re-formatted to be consistent throughout.

* gitingore

* refactor fatal handling

* updated docs for API and added sequence diagrams.

* making sure that git checkout of tags, doesn't get incrementing numbers when master gets more commits