cover: tweak styles:

- `optimizeQuality` > `smooth` (CSS language evolution)
- Use `auto` instead of a fixed width.
- Add exceptions for heights and apply them to some previously modified templates.
- Remove `is-large` exception.
- Widen the content column on list curation.

bookwyrm/templates/user/user.html

@@ -36,7 +36,7 @@
             {% for book in shelf.books %}
             <div class="control">
                 <a href="{{ book.local_path }}">
-                {% include 'snippets/book_cover.html' with book=book cover_class='is-medium' %}
+                {% include 'snippets/book_cover.html' with book=book cover_class='is-h-medium' %}
                 </a>
             </div>
             {% endfor %}