------------------------------
* ``linkify()`` has changed considerably. Many keyword arguments have been
replaced with a single callbacks list. Please see the documentation for more
information.
* Bleach will no longer consider unacceptable protocols when linkifying.
* ``linkify()`` now takes a tokenizer argument that allows it to skip
sanitization.
* ``delinkify()`` is gone.
* Removed exception handling from ``_render``. ``clean()`` and ``linkify()`` may
now throw.
* ``linkify()`` correctly ignores case for protocols and domain names.
* ``linkify()`` correctly handles markup within an <a> tag.