TYPO3: debug language labels backend

revision 690aa2ffcc2cce2136b5b8da1390e9c3b9c9aec9

Show the full language label paths in the backend:

$TYPO3_CONF_VARS['BE']['lang']['debug'] = true;

In TYPO3 8, this is different:

$TYPO3_CONF_VARS['BE']['languageDebug'] = true;