HTML Purifier 4.8.0 is a bugfix release, collecting a year
of accumulated bug fixes.  In particular, we fixed some minor
bugs and now declare full PHP 7 compatibility. The primary
backwards-incompatible change is that HTML Purifier will now
add rel="noreferrer" to all links with target attributes
(you can disable this with %HTML.TargetNoReferrer.)  Other
changes: new configuration options %CSS.AllowDuplicates and
%Attr.ID.HTML5; border-radius is partially supported when
%CSS.AllowProprietary, and tel URIs are supported by default.