Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #2281619 by dawehner, tim.plunkett: Convert most direct usages within module code of routing related request attributes to use RouteMatchInterface instead

Issue #2363139 by Wim Leers, dawehner, larowlan: _content controllers may only return render arrays, not strings.

Issue #2160965 by herom, dawehner, robertdbailey, Berdir, fran seva: Fixed Content entities are not upcast in the page language, inconsistent with config entities.

Issue #340723 by ParisLiakos, sun, Berdir, glennpratt, Cottser, swentel, alexpott, tstoeckler, Xano, tim.plunkett, BassistJimmyJam | beejeebus: Make modules and installation profiles only require .info.yml files.

Revert "Issue #340723 by ParisLiakos, sun, Berdir, glennpratt, Cottser, swentel, tstoeckler, Xano, tim.plunkett, BassistJimmyJam: Make modules and installation profiles only require .info.yml files."

This reverts commit b4c561d0.

Issue #340723 by ParisLiakos, sun, Berdir, glennpratt, Cottser, swentel, tstoeckler, Xano, tim.plunkett, BassistJimmyJam: Make modules and installation profiles only require .info.yml files.

Issue #2051097 by dawehner, Manuel Garcia, tlattimore, neclimdul: Change 'pattern' to 'path' in *.routing.yml files.

Issue #1981368 by tim.plunkett, Crell, webchick: Convert all routes to 'module_name().foo_bar()' naming convention.

Issue #2031487 by fubhy, dawehner, pwolanin:  When replacing the upcasted values in the request attributes array, retain the original raw value too.

Issue #1943846 by fubhy, effulgentsia, tim.plunkett: Improve ParamConverterManager and developer experience for ParamConverters.

Issue #1818556 by das-peter, plach, fago, Berdir, vijaycs85: Change notice: Convert nodes to the new Entity Field API.

Issue #1798214 by tnightingale, g.oechsler, fubhy, katbailey, effulgentsia, Crell, dipen chaudhary: Upcast request arguments/attributes to full objects.