* test case added to avoid adding them later

Fix #4823

use fetch method instead of fetchRow because fetchRow is only an owncloud internal alias that exists purely for compability

provide a way to detect the language that is being used (e.g. for clientside javascript language selection

Fixed:
- An error with a misplaced bracket in lib/private/util.php
- An error with an incorrect function being called in lib/public/contacts.php

Some things my IDE complained about while creating a custom backend.

Fix PHPDoc and typos

Some things my IDE complained about while creating a custom backend.

Conflicts:
	lib/private/group/database.php
	lib/private/group/dummy.php
	lib/private/group/example.php

Make sure to correctly check for string emptiness when the passed path
is "0".

can restore them if needed