1. Configure font color (enable or not) in book style
2. Show text statistics (# of nouns, verbs, etc.) by paragraph, markdown, page and book
3. Import Blogger: add published date to the content
4. Embed YouTube playlist
5. Storage: quickly delete all generated files for books
6. Support WebP image file
7. Fix bug for keyboard shortcuts (copy, cut, paste)
8. Bug fix
