Remove magic quote handling from $_GET / $_POST
The magic quote functionality was removed with PHP 5.4.0.
In previous PHP versions this was a switch to turn on/off adding
slashes to the _GET and _POST superglobals.
TYPO3 however was always adding slashes at every request
and using GeneralUtility::_GP() etc. to remove the slashes again.
As the PHP functionality is now removed, meaning there are no
slashes added at all, TYPO3 can now use the non-slashed data
inside the superglobals directly.