Issue #2712647 by slasher13, klausi, catch, jibran, Manuel Garcia, alexpott, mpdonadio, naveenvalecha, neclimdul, timmillwood, webflo, dawehner, Wim Leers, pounard: Update Symfony components to ~3.2

Issue #2776975 by joelpittet, dawehner, tim.plunkett, xjm, pfrenssen: March 3, 2017: Convert core to array syntax coding standards for Drupal 8.3.x RC phase

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2497243 by Fabianx, znerol, fgm, Wim Leers, darol100, jhedstrom, hussainweb, pfrenssen, neclimdul, jibran, Nitesh Sethia, dawehner, chx, catch, benjy, Aki Tendo: Replace Symfony container with a Drupal one, stored in cache