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

Issue #2040135 by Wim Leers, Berdir: Caches dependent on simple config are only invalidated on form submissions

Issue #2216961 by Gábor Hojtsy, xjm | alexpott: Document Config, ConfigBase, and StorableConfigBase.

Issue #2215413 by Eli-T, alexpott: Split the Config class into StorableConfigBase and ConfigBase. Make ThemeSettings inherit from ConfigBase.

Issue #1712250 by alexpott, n3or, cam8001, vijaycs85, Albert Volkman, jibran, heyrocker, chx: Convert theme settings to configuration system.