Temporary revert; CMF 1.3 is also ready and is a bigger PITA to re-roll.

This reverts commit d806a9bb.

Issue #2234277 by cilefen, hussainweb, Xano, netlooker, martin107: Composer update (includes security fixes).

Issue #2313669 by dawehner, hussainweb, pfrenssen: Bring in egulias/EmailValidator for RFC compliant email address validation.

Issue #2303673 by dawehner, damiankloip, effulgentsia, Fabianx: Implement stackphp; cleanup handlePageCache() and preHandle()

Issue #2316537 by dawehner | chx: Upgrade symfony CMF to 1.2, remove deprecated parameters from getRouteByName* .

Issue #2073811 by dawehner, pwolanin, joelpittet, Cottser, Mark Carver, steveoliver: Add a url generator twig extension.

Issue #2294439 by dawehner, sun | neclimdul: Add vfsStream library for filesystem mocking in unit tests.

Issue #1959660 by larowlan, pfrenssen, xjm, clemens.tolboom, dawehner, RobLoach: Replace xpath() with WebTestBase::cssSelect() by leveraging Symfony CssSelector.

Issue #1851234 by alexpott: Slow yaml parsing slows down tests which load/save many config files (e.g. views).

This caused a conflict in the language objectification patch. Postponing.

This reverts commit 9e017ada.

Issue #2151829 by dawehner, chx: Doctrine annotation parsing takes an unacceptable amount of time/memory on install.