Issue #2851394 by GoZ, hgunicamp, oknate, jungle, wolffereast, tameeshb, mmatsoo, ridhimaabrol24, jofitz, swarad07, tanc, shaktik, dimaro, shashikant_chauhan, MerryHamster, quietone, nitesh624, martin_q, boaloysius, gaurav.kapoor, nitvirus, ankithashetty, Munavijayalakshmi, kostyashupenko, leolando.tan, amit.drupal, ravi.shankar, akashkrishnan01, Swapnil_Kotwal, Saviktor, mrinalini9, anmolgoyal74, Venkatesh Rajan.J, shimpy, lomasr, Dinesh18, shubham.prakash, mahtab_alam, markdorison, cilefen, longwave, bleen, xjm, alexpott, gmaltoni: Fix grammar 'a' to 'an' when necessary

Issue #2691675 by Berdir, Mile23, alexpott: Replace deprecated entityManager() in ControllerBase descendents

Issue #2684213 by amateescu, larowlan, josephdpurcell, dawehner: Preview on forward node revisions throws an error

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

Issue #2545972 by alexpott, joelpittet, ericjenkins, stefan.r, Wim Leers, Cottser: Remove all code usages SafeMarkup::checkPlain() and rely more on Twig autoescaping

Issue #2457887 by prateekMehta, stefan.r, rpayanm, alexpott: Use Utility\SafeMarkup class instead of Utility\String for placeholder(), checkPlain(),format() functions

Issue #2350877 by dawehner, Wim Leers, hussainweb: Deprecate/rename drupal_add_feed(), drupal_add_html_head(), drupal_add_html_head_link(), drupal_add_http_header(), and allow to be set declaratively in #attached.

Issue #1510544 by swentel, Bojhan, Gábor Hojtsy, merlinofchaos, Cottser, Wim Leers, plopesc, aspilicious, sannejanssen,  larowlan, tim.plunkett, nod_: Fixed Show previews in front-end theme, able to select different view modes.