4.11.0

This release focuses on fixes to the produced EPUBs to make them valid. Previously certain chapters, or parts of the metadata, were broken, which would lead to either those chapters or the entire book being unreadable, depending on the e-reader software in question.

Thanks to @Es7evam for pointing these issues out, in #22!

• Fixed invalid XHTML in Worm Interlude 8 (Bonus), Worm Cockroaches 28.2, and Ward Sundown 17.6.
• Replaced <img>s referencing a WordPress-hosted skeptical face with a textual 🤨 emoji.
• Fixed various issues with the covers' metadata and XHTML.
• Removed the compression of the mimetype file in the generated EPUB, since apparently that's disallowed per the EPUB spec.