…e sanitizing engine.

- The *attribute exceptions* feature has been removed in favor of DOMPurify's configuration options. The `addAttributes()` and `removeAttributes()` methods no longer exist.
- Reef now offers a smaller *unsafe* version for UIs that don't use any third-party or user-provided content. It does *not* sanitize templates before rendering, so use with caution.
- SVGs are now properly supported and will render correctly.