Revert "Issue #2459753 by tim.plunkett: EntityForm::validate() should be able to modify the form structure"

This reverts commit d4d83576.

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

Issue #2322639 by hussainweb, LinL, Temoor, oenie, MKorostoff, mglaman, kyuubi, unstatu, omers, pcambra, legolasbo, benjy, JeroenT: Replace all instances of node_type_load(), node_type_get_types(), entity_load('node_type') and entity_load_multiple('node_type') with static method calls from DRUPAL SOUTH WOOOO!

Issue #2384481 by rpayanm, daffie, tadityar, hussainweb, areke, claudiu.cristea: Make the class variables protected for NodeType

Issue #2355909 by penyaskito, alexpott, Gábor Hojtsy, DuaelFr: language.settings config is not scalable

Issue #2321385 by alexpott, bircher, amateescu, swentel, benjy: Fixed Creation of node body field in postSave() incompatible with default config and overrides.

Issue #2277103 by tim.plunkett, pwolanin, Wim Leers, dawehner, hotpizzas: Switch Drupal::l() and LinkGenerator to expect a Url object.

Issue #2343651 by xjm, tim.plunkett, Wim Leers, dinarcon, dawehner: Remove most remaining l() calls.

Issue #1182850 by xjm, Stefan Lehmann, jmcintyre, Bojhan: Remove full stops at the end of checkbox options.

Issue #2335659 by tim.plunkett, dawehner, effulgentsia, sun: Remove FormState ArrayAccess usage from core.

Issue #2324121 by Berdir, slashrsm, alexpott: Fixed NodeType's settings array was meant to be able to store information from mutliple modules.

Issue #2283977 by alexpott, Gábor Hojtsy, effulgentsia, fago: Create a new ConfigEntity type for storing bundle-specific customizations of base fields.

Issue #2308821 by tim.plunkett: Replace FormErrorInterface with $form_state->setErrorByName() and $form_state->setError().

Issue #2272481 by herom, ParisLiakos, tim.plunkett: Remove usages of watchdog() from forms, plugins and controllers.

Issue #2229163 by Michael Hodge Jr, rixter, thechanceg, bburg | Berdir: Remove node_type->has_title.

Issue #2084323 by Berdir, sandipmkhairnar, Xano, Jalandhar: EntityForm::actions() adds 'delete' without checking access.

Issue #1709960 by Berdir, zserno, jessebeach | joachim: Declare a maximum length for entity and bundle machine names.

Issue #2002246 by tompagabor, floretan, lauriii, pakmanlh, rbomhof | pixelite: Capitalize operations links in the comment and taxonomy term admin UI.

Issue #2203407 by nod_, sun: Replace #attached library array values with provider-namespaced strings.

Issue #2170425 by miraj9093, sandipmkhairnar, tgeller: Make text consistent: "Add new content" -> "Add content".

Issue #2053461 by larowlan, andypost, tim.plunkett, swentel: Node type settings such as published state, promoted state, create revision and author information cannot be turned off.

Issue #2145007 by tim.plunkett, h3rj4n: Convert form_set_error() in FormBase classes to use FormErrorInterface.

Issue #2113319 by Xano: Rename getOriginalID() to getOriginalId() and setOriginalID() to setOriginalId().

Issue #2102465 by vijaycs85, ACF, InternetDevels, sidharthap: Remove drupal_set_title() in node module controllers.

Issue #2025991 by plach, David Hernández: Introduce hook_entity_prepare() to generalize hook_node_prepare().