Issue #2123251 by Jelle_S, marcvangend, attiks, Sutharsan: Improve DX of responsive images; convert theme functions to new #type element

Issue #2349461 by Jelle_S, mdrummond, attiks, Wim Leers: Move fallback image style into the responsive image style entity

Issue #2457271 by rteijeiro, Palashvijay4O, Cottser: More cleanup of the 'themeable' documentation group

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

Issue #2273923 by mpdonadio, pfrenssen, effulgentsia, pcambra, xjm, tim.plunkett, martin107, cilefen: Remove html => TRUE option from l() and link generator

Issue #2260061 by Jelle_S, attiks, Wim Leers, mdrummond, mgifford, holist: Responsive image module does not support sizes/picture polyfill 2.2

Issue #2091321 by er.pushpinderrana, jhodgdon, rootwork, ifrik, mparker17: Update hook_help for Field and Field UI module

Issue #2350837 by dawehner, Berdir, larowlan, Wim Leers: Convert most usages of EntityInterface::getSystemPath() to use routes

Revert "Issue #2273923 by mpdonadio, pfrenssen, dawehner, xjm, cilefen: Remove html => TRUE option from l() and link generator"

This reverts commit 0bcabf50.

Issue #2273923 by mpdonadio, pfrenssen, dawehner, xjm, cilefen: Remove html => TRUE option from l() and link generator

Issue #2349859 by R. Volk, naxoc: Responsive Image Mappings :: throws a fatal exception if no image style is set

Issue #2322037 by oenie, Temoor, jepSter, rpayanm: Replace all instances of responsive_image_mapping_load(), entity_load('responsive_image_mapping') and entity_load_multiple('responsive_image_mapping') with static method calls.

Issue #2226207 by lauriii, mgbellaire, Cottser, m1r1k, Mark Carver, LinL, rachel_norfolk, rteijeiro, skwashd, davidhernandez, euphoric_mv: Make 'template' the default output option for hook_theme().

Issue #2343661 by larowlan, tim.plunkett | xjm: Rename l() to _l() and url() to _url(), and document replacements.

Issue #2328411 by dawehner, geerlingguy, herom: Convert all permissions to yml files and permission callbacks.

Issue #2271529 by attiks, alexpott, Lowell, YesCT, Jelle_S | mdrummond: Move breakpoint settings to theme and module *.breakpoints.yml files at root level.

Issue #1825952 by Fabianx, joelpittet, bdragon, heddn, chx, xjm, pwolanin, mikey_p, ti2m, bfr, dags, cilefen, scor, mgifford: Turn on twig autoescape by default

Issue #1999312 by baisong, lokapujya, botanic_spark, attiks: Add an 'empty image' option for responsive image.

Issue #2190313 by pfrenssen, Berdir, amateescu, ianthomas_uk: Add $EntityType::load() and loadMultiple() to simplify loading entities.

Issue #2183113 by jhodgdon, effulgentsia, tim.plunkett, herom, larowlan: Update hook_help signature to use route_name instead of path.

Issue #2222431 by TechNikh, visabhishek, YesCT, jhodgdon: Project name clean up after Picture module renamed Responsive Image.

Issue #2226903 by pwolanin, dawehner, tvn, martin107, jessebeach: Step 1: Move static menu links to yml files.

Issue #2178725 by pwolanin, crowdcg, effulgentsia, Sutharsan: Make all core menu link machine names and the corresponding route names match.

Issue #2124377 by ellishettinga, Jelle_S, attiks, mdrummond, Schnitzel, InternetDevels: Rename "Picture" module to "Responsive Image" module.

Issue #1996238 by sun, nod_, damiankloip, Wim Leers, longwave, alexpott, Xano, mdrummond, Mark Carver, Jeff Burnz, highrockmedia, joelpittet, et al: Replace hook_library_info() by *.libraries.yml file.

Issue #2033415 by tankerjoe, lostkangaroo, batigolix, sandipmkhairnar, m1n0: Fix up hook_help for picture module

Issue #2047633 by pwolanin, dawehner, kim.pepper, Xano, amateescu, tim.plunkett: Move definition of menu links to hook_menu_link_defaults(), decouple key name from path, and make 'parent' explicit.

Revert "Issue #2047633 by dawehner, pwolanin, Xano, amateescu, tim.plunkett: Move definition of menu links to hook_menu_link_defaults(), decouple key name from path, and make 'parent' explicit."

This reverts commit 531fd593.