Introducing LunaBuild to the build flow (#36)

Introducing LunaBuild to the build flow (#36)

* add LunaBuild for better control of source file selections

* remove out-dated template based method
* add LBuild files that follow LunaBuild methodology

* integrate LunaBuild into the building flow

* add documentation on general usage of LunaBuild
* fix `make run` does not work properly

* implement and integrate LConfig language

* implement LConfig language for modularised kernel build experience
* integrate LConfig into build flow
* clean up out-dated files

* Add interactive shell to do configuration

* file clean up

* General clean up

* move grub image stuff to scripts/grub
* remove the code format rule file - we don't need these fancy shit!

* refine the config shell experience

* allow accessing node using posix-path
* able to identify whether the configuration is aborted or exit normally

* fix up the dependencies in makefile, rebuild when needed

* make sure the configuration shell only pop up when:
  1) LConfigs changed
  2) config.h disappeared
* add proper implementation on header files change detection
* add missing doc string on some config nodes