TYPO3 Core

The typo3/ directory must currently be exposed in the web root for TYPO3 to work properly.
Having the vendor dir with all composer dependencies in typo3/vendor however means, that
these will also be exposed. This can be a security risk, which can be avoided by simply
moving the vendor directory one level up.

By doing so, a web directory which contains only two symlinks (typo3 and index.php) and no
sources or link to the sources, will be protected from this risk.