[FIX] 0024309: FileAlreadyExistsException thrown when downloading folders containing files with the same name

As announced on 2019-05-19 via developers@ and PR, this commit introduces the
[new ILIAS coding style](https://github.com/ILIAS-TechnicalBoard/ILIAS/blob/trunk_coding_style/docs/documentation/coding-style.md)
to release_6.

fixed bug #26482: \ilObjSurvey::checkConstraint: count(): Parameter must be an array or an object that implements Countable