Replace @returns with @return, in /lib
Fix @return array PHPDocs, in /lib
Squash 'a | b' into 'a|b', in /lib
Fix all PHPDoc types and variable names, in /lib
Change parameter type for useBackend
Fix PHPDoc and typos

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
Use OC_User_Interface instead of OC_User_Backend
Fix Scrutinizer errors about missing user backend
Change parameter order of implode
Fix Scrutinizer errors
Fix various code errors detected by Scrutinizer

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
More PHPDoc for file functions
fixing typo and missing @throws
adding PHPDoc
object -> \OC\Preview
fix PHPDoc
@breif -> @brief
@returns -> @return
fixing variable naming
Merge pull request #8542 from owncloud/phpdoc-improvements

PHPDoc Improvements