[TYPO3-project-4-3] no prefix for TYPO3 BE classes

[Martin Kutschker]

Hi!

None of the classes within typo3/classes have a prefix. As PHP < 5.3 has
no namespaces there could be conflicts. I suggest therefore that we
change this and add a "typo3_" prefix to them.

As they are not part of the official API I think this is ok without
providing compatibility code (wrappers). Simply changing the XLCASS code
 in extensions is enough to adapt to this change.

Masi