Cosmetic changes

[CodeFetch]

I'd like to propose a few style changes like:

• using imperative form for comments describing an action
• using tabs for indentation instead of spaces
• defining variables at the beginning of a function
• global includes first
• dropping curly braces of for/if-constructions with a single command
• requiring basic C knowledge from the reader like int == 0/pointer == NULL equals !int/!pointer