Revert "TYPO3 6.2 Compatibility: Use EXT: in hooks, ext_autoload does not work anymore"

Reverted due to "Fatal error:  Class 'tx_varnish_controller' not found" in TYPO3 6.2 (autoloader still seems to work fine)

This reverts commit af56fd9f0ff27bba5218e453b293b8a9f513d578.