[CLEANUP] #4320 Add more type hinting

Change-Id: Id28c03b9412feaca1fcc692b1be047e1921ee256
Reviewed-on: http://review.typo3.org/35608
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>