Select coding conventions & auto formatting

[JSYoo5B]

When you see the codes as raw text, it has mixed tabs and spaces.

Also, comments are written in /* */ and //.
(FYI, the /* */ is basic commenting notation in old C standard, // were back-ported from C++ standard)
I don't want to force use /* */ for all the comments, but it may be effective by setting each commenting notation into its specific meaning.
ex. use /* */ for documentation formatting comments, use // for general comments in code blocks.

Maybe there would be some other things to consider for standard coding conventions in this project.
After selecting coding conventions, auto-formatting and style check automation may be required. It will improve PR review (not arguing with minor coding styles, reducing meaningless formatting commits)
Anyone who has some opinions about coding conventions, please write your opinions here.

[JSYoo5B]

Auto formatting will be handled by clang-format.

[onting]

It seems better to unify intent char to 4 spaces.
Additionally, the /* */ style would fit within information of API in header files(even though i didn't write in this style).
And // would be good for subrootine flow comments.

[onting]

Auto formatting will be handled by clang-format.

I'll check it out.