Issue #2380389 by webflo, Mile23, davidwbarratt, timmillwood, hussainweb, tstoeckler, bojanz, yched, MKorostoff, alexpott, webchick: Use a single vendor directory in the root

Issue #2406681 by tstoeckler, hussainweb, alexpott, ParisLiakos, almaudoh, tadityar: Add an autoload.php in the repo root to control the autoloader of front controllers