Quill Delta To Html Versions Save

See https://github.com/nozer/quill-delta-to-html/issues/38

Thanks to @volser

Possibly breaking change

Changed the way urls are sanitized. Absolute urls must be provided for links, media, etc. Urls with unsupported protocol are prepended with unsafe:. Supported protocols are: http:, https:, ftp:, sftp, file:, blob:, mailto:, tel:, data:image/

Fixed tests

Added type definitions

Made link target attribute configurable and allowed individual ops to override it

Fixed extra lines in <pre> and added validation and tests for mentions

Releasing contributed the support for image width attribute.

• new option to set rel attribute on links
• new option to allow non hex values on color attributes
• add css classes to background attribute

Thanks @iddanh