Issue #2543334 by Wim Leers, lauriii, Fabianx: Auto-placeholdering for #lazy_builder with bubbling of contexts and tags

Issue #2549791 by alexpott, Wim Leers: Remove SafeMarkup::xssFilter() and provide ability to define #markup escaping strategy and what tags to filter

Issue #2551335 by alexpott, Wim Leers: Remove unnecessary SafeMarkup usage in tests and clear the static cache before every run

Issue #2542830 by borisson_, PieterJanPut, RavindraSingh, Wim Leers, catch: Change placeholder token generation from using sha1 to crc32b

Issue #2543332 by Wim Leers, effulgentsia, Fabianx, Crell, dawehner, borisson_: Auto-placeholdering for #lazy_builder without bubbling

Issue #2506581 by alexpott, Wim Leers, Fabianx, xjm, joelpittet, Cottser, dawehner: Remove SafeMarkup::set() from Renderer::doRender

Issue #2505989 by alexpott, dawehner, olli: Controllers render caching at the top level and setting a custom page title lose the title on render cache hits

Issue #2273925 by larowlan, aneek, lauriii, mikey_p, joelpittet, dimaro, Fabianx, xjm, jaredsmith, effulgentsia, lokapujya, iMiksu, chx, YesCT, googletorp, dawehner, Wim Leers, Cottser: Ensure #markup is XSS escaped in Renderer::doRender()

Issue #2478483 by Wim Leers, Fabianx: Introduce placeholders (#lazy_builder) to replace #post_render_cache