Bleach supports adding html5lib filters to the cleaning process, which
is how its linkify() process works, as well as being how I implemented
the custom Tildes linkification for usernames and group names.
This commit switches to adding those filters into the clean() call,
which makes it so everything is now done in a single pass instead of
three. In addition, this also fixes the issues we were having with
bleach "fixing" things that it thought were invalid HTML (when they were
just people writing things inside angle brackets).
Deimos
23e2a1b65c