refactor(scanner): code cleanup

[ObserverOfTime]

• Use local import for parser.h
• Use the new built-in array API
• Define DELIMITER_LENGTH constant
• Mark simple functions as inline
• Remove functions that are only used once
• Remove rarely used mark_end function
• Simplify scan_whitespace_and_comments function
• Use bitwise and instead of modulo
• Various codestyle improvements

[ObserverOfTime]

Hello? :)

[VladimirMakaev]

This looks good to me, but I'd prefer @fwcd to merge this. In the meanwhile can you please rebase on master there are a bunch of things changed and versions upgraded since you original sent this PR

[fwcd]

Thanks!