Ignore binary, changed name of the source file

* 출력파일 무시
* main.c 로 소스코드 이름 변경
Used `bool` instead of #define TRUE/FALSE

* TRUE / FALSE -> true / false
* Exit code of a program should be 1 not 0 in error case
Cleaned redundant code

* Deleted unreachable code
* Made code DRY
* if(condition) return true; else false;
  -> return condition
Removed meaningless code

* No self repeat
Made code more safe

* I hate #define
* scanf("%s", &buffer) is harmful
Changed whitespace character of the code in my taste

* tab -> space*2
Added Makefile

* Just call `make` when you want to build it
Updated .gitignore, ignoring *.exe file

* 실행파일 repo에서 제외
Merge pull request #1 from simnalamburt/master

친절한 설명 감사! 하나하나 뜯어 보고 모르는 거 있으면 물어봐도 되지? ㅎㅎ