[CLEANUP] RTE plugin classes

[CLEANUP] RTE plugin classes

* use statements
* Use default values from abstract class
* Fix tons of comments
* Some obvious code simplifications

Change-Id: I844efbf830cf2506f2b9c7caadd6826dc67718e9
Resolves: #67323
Releases: master
Reviewed-on: http://review.typo3.org/40036
Reviewed-by: Frank Nägler <typo3@naegler.net>
Reviewed-by: Jan Helke <typo3@helke.de>
Tested-by: Jan Helke <typo3@helke.de>
Reviewed-by: Susanne Moog <typo3@susannemoog.de>
Tested-by: Susanne Moog <typo3@susannemoog.de>