Fixed bug #15576: Enable customization for fatal error messages in the backend...

Fixed bug #15576: Enable customization for fatal error messages in the backend and frontend / Make all page errors RuntimeExceptions and unify BE and FE fatal errors in a single HTML template (Thanks to Reinhard Führicht, Aske Ertmann) - Part 2 - Usecases


git-svn-id: https://svn.typo3.org/TYPO3v4/Core/trunk@9099 709f56b5-9817-0410-a4d7-c38de5d9e867