Issue #3421017 by mohit_aghera, smustgrave: Convert LanguageNegotiation plugin discovery to attributes

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

Issue #2195573 by Xano, eiriksm, heddn, ParisLiakos, Les Lim, Pere Orga, dinarcon, xjm, alexpott: Add a dedicated @LanguageNegotiation annotation class

Issue #2347465 by tim.plunkett, dawehner, cilefen: Convert all instances of #type link/links to convert to use routes.

Issue #2080427 by connork, blainelang, harijari, areke, chertzog: Remove Unused local variables from language module.

Issue #1862202 by plach, Berdir, katbailey, ParisLiakos, alexpott, chx, sun, larowlan, Gábor Hojtsy, cosmicdreams, vijaycs85, YesCT, penyaskito, andypost, Albert Volkman, joelpitett: Objectify the language system.