Issue #3421012 by sorlov, quietone, sakthi_dev, mstrelan, Wim Leers: Convert Filter plugin discovery to attributes

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

Issue #2217877 by Wim Leers, Dave Reid, damiankloip, xjm, chx | catch: Fixed Text filters should be able to add #attached, #post_render_cache, and cache tags.

Issue #2099741 by Wim Leers, wwalc, mr.baileys, eaton, dstol, nod_, effulgentsia: Protect WYSIWYG Editors from XSS Without Destroying User Data.