Issue #2569119 by pwolanin, marvin_B8, jhedstrom, csheltonlcm, alexpott, dawehner, Fabianx, catch:  Use Crypt::hashBase64(), not hash('crc32b') or sha1 for placeholder tokens

Revert "Issue #2712647 by klausi, catch, slasher13, jibran, Manuel Garcia, alexpott, naveenvalecha, neclimdul, dawehner, Wim Leers, pounard: Update Symfony components to ~3.1"

This reverts commit a55b8ef1.

Issue #2712647 by klausi, catch, slasher13, jibran, Manuel Garcia, alexpott, naveenvalecha, neclimdul, dawehner, Wim Leers, pounard: Update Symfony components to ~3.1

Issue #2783393 by Mile23: Fix 'Drupal.Commenting.FunctionComment.IncorrectParamVarName' coding standard

Issue #2749819 by Fabianx, dawehner: OptimizedPhpArrayDumper does not resolve references via aliases correctly

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