[RFC] Refactor main.c

[mhinz]

Change main.c according to project's coding guideline.

[felipecrv]

Can't we delay massive style changes? :( ping @justinmk @tarruda

[aktau]

Well it does look cleaner now, whether it be integrated now or in the future! I still see TRUE and FALSE though, you can lowercase those (even if you don't change the types to bool. (but preferable is looking if the type can be changed to bool though).

[KarboniteKream]

@aktau I'm doing this in my PRs. I think it's better to leave those as they are, since it's easier for me to track, which were changed.

[justinmk]

@mhinz If you are ok with licensing your past contributions under Apache 2.0, would you mind signing the CLA? See #883