[CLEANUP] Code Cleanup EXT:feedit

Refactor the code to go green in PHPStorm.
Main tasks:
* Initialize variables
* Centralize objects in $GLOBALS

Resolves: #62691
Releases: master
Change-Id: Iaf4659bc9ef4cdeffbccd53fde2969a9b4c592c4
Reviewed-on: http://review.typo3.org/33785


Reviewed-by: Jan Helke <typo3@helke.de>
Tested-by: Jan Helke <typo3@helke.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>