Tracking Issue: Compile-time Configuration Framework

[Rain336]

Tracking issue for #3

• Implement the config! proc-macro function (Start of the Configuration Framework #6)
• Implement the #[config::cfg(...)] proc-macro function (Add more configuration macros for the configuration framework #7)
• Implement the #[config::cfg_attr(..., ...)] proc-macro function (Add more configuration macros for the configuration framework #7)
• Implement CLI tool - Line Args Mode
• Implement CLI tool - Terminal UI Mode

[Rain336]

Will put this on hold for now, I started working on the CLI tool but I now kinda question it's usability. The Terminal UI tool would be nice though. Am generally not that confidant in the current state of the configuration framework and might need to go back to the drawing board on it a bit.