Issue #3104307 by Berdir, longwave, Gábor Hojtsy, Wim Leers, alexpott, andypost: Remove  BC layers in various Drupal\Core components

Issue #3048498 by jonathan1055, Lendude, naveenvalecha, klausi, alexpott, Gábor Hojtsy: [≈Nov. 11] Fix Drupal.Commenting.Deprecated coding standard

Issue #3021450 by kim.pepper, jibran, voleger, alexpott, Berdir: Add @trigger_error to deprecated functions in file.inc and replace their usages

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 #2531570 by mondrake, MattA, claudiu.cristea: Image objects should release memory when losing scope

Issue #2491155 by mikeburrelljr, Mac_Weber, opdavies: Update drupal.org and kernel.org URLs in core modules (Follow-up to 2489912)

Issue #2063373 by mondrake, claudiu.cristea, larowlan, arunvs: Fixed Cannot save image created from scratch.

Issue #2330899 by attiks, Jelle_S, fietserwin: Allow image effects to change the MIME type + extension, add a convert image effect.

Issue #2211227 by mondrake, xjm | fietserwin: Refactor image and imagetoolkit: isExisting, isSupported, supportedTypes, getMimeType.

Issue #2217783 by mondrake: Remove $extension and $mimeType from Image, use image_type_to_xxx function in the getters instead.

Issue #2103621 by mondrake | fietserwin: Move GD logic from ImageInterface to toolkit, tie toolkit instance to Image instance, toolkits should no longer be instantiated separately.

Issue #2048827 by claudiu.cristea, tim.plunkett: Move Image toolkit API from system.module to Drupal\Core.