[CLEANUP] Cleanup ext:core

* Add phpDoc to properties
* Add phpDoc to functions
* Shorten class names where possible

Resolves: #62707
Releases: master
Change-Id: I763595103127d79af8abcb3ebcfb6b3767df9451
Reviewed-on: http://review.typo3.org/33804
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>