Issue #2294129 by xjm, tim.plunkett: Switch hook_help() to use RouteMatch instead of Request.
Issue #2272279 by joelpittet, chx: Kill RenderWrapper class.
Issue #2293723 by yched: Generate lighter $form[$field] structures.
Issue #2293723 by yched: Generate lighter $form[$field] structures.
Issue #2087965 by AndyThornton, neclimdul, tim.plunkett, jhodgdon, pwolanin: Fixed The SearchPluginManager needs to provide an alter hook for its discovery.
Issue #2239009 by effulgentsia, dawehner: Remove public direct usage of the '_system_path' request attribute.
Issue #1875996 by Xano, tim.plunkett, neclimdul, Rajendar Reddy, Jalandhar: Reconsider naming conventions for derivative classes.
Issue #2292815 by larowlan, joshi.rohit100, andypost: Remove join comments on users table.
Issue #2293163 by Wim Leers, pwolanin: Fixed MemoryBackend's cache entries may be modified unintentionally thanks to object references.
Issue #2293063 by Gábor Hojtsy: Fixed Config schema mapping parsing is inconsistently forgiving, does not conform to the interface.
Issue #2144263 by fago, yched, alexpott, Berdir, plach, andypost, effulgentsia, michaelfavia: Decouple entity field storage from configurable fields.
squash all the work by Wim Leers, dawehner, pwolanin, berdir, effulgentsia, likin, and plach
 May 28 - rebase for #2267753 and #2214209 and PSR-4 and multi-load fixes
 June 14 - rebase for minor conflicts with 8.x, includes manager class split
 June 20 - rebase for minor conflicts with 8.x, includes test and caching fixes
 July 1 - squash merge and fix conflicts due to RouteMatch change and memory cache fix #2293163
rename class to MenuTreeElement