extend lang file cascade, so users can override some lang strings

Fixes #692
add lang files to cascading
reformatting config cascade
use config cascade for loading of localizations
visibility plugin methods
Merge remote-tracking branch 'origin/master' into overridablelangstrings

Conflicts:
	inc/plugin.php
improve some scrutinizer issues

different types
unused vars
PHPDocs
phpdocs parserutils
Merge pull request #708 from splitbrain/overridablelangstrings

extend lang file cascade, so users can override some lang strings