Issue #1894002 by scor, msonnabaum, effulgentsia: Update vendor libraries and pin them to specific versions in composer.json.
Issue #1424924 by Rob Loach: Added Use Composer for updating Symfony components (without removing Symfony code from repo).
- Patch #1497182 by Crell, BTMash: Update to latest Symfony 2.1 code. This is commit c4dfe931f1ce8827f8c02975bc0ab405bdc8d27c out of Symfony.
Issue #22336 by quicksketch, scor, boombatower, and rfay. Move all core Drupal files under a core subdirectory.