Improve config implementation

[JanWielgus]

Now config.h and config.cpp is done in a pre-c++17 way. It is good but can be better using c++17 standard. Example constant in a config.h:

inline constexpr uint8_t ExampleConstant = 5;

Make all config variables looks like it. At the end remove the config.cpp file.

Links that I found helpful:

• https://stackoverflow.com/questions/38043442/how-do-inline-variables-work/53896763#53896763
• https://stackoverflow.com/questions/14391272/does-constexpr-imply-inline
• https://stackoverflow.com/questions/50488831/use-of-constexpr-in-header-file
• https://isocpp.org/blog/2018/05/quick-q-use-of-constexpr-in-header-file
• https://stackoverflow.com/questions/16287776/static-constexpr-variable-vs-function