Beta release.
- LAZY_SRCSET_ENABLED setting added. By default it is the opposite of DEBUG.
- default_size can be set using a kwarg if needed.
- format_html() replaces previous stringification.
- LAZY_SRCSET_THRESHOLD setting added. This can be used to prevent images of a similar width from being created.
- Sizes can now be either an integer or a string with vw or px units.
- When a size is defined with px it ignores the threshold and will always be made.