[TASK] Cleanup code base

* Use new license header
* Use shorter check for TYPO3_MODE
* Use real booleans where possible
* Remove some SVN leftovers

Resolves: #61576
Releases: 0.6
Change-Id: I6b14615ed4846b4bbc485279695ed3e939a45b2b
Reviewed-on: http://review.typo3.org/32761
Reviewed-by: Francois Suter <francois@typo3.org>
Tested-by: Francois Suter <francois@typo3.org>