New features: added kepub3 output format: Kobo-instrumented EPUB using EPUB3 package/navigation semantics.
- Existing kepub remains unchanged as OPF2-style Kobo output.
- kepub3 uses .kepub.epub extension, nav.xhtml, EPUB3 metadata, EPUB3 cover manifest properties, and EPUB3 floating footnote markup.
- Kobo-specific XHTML wrapping and koboSpan sentence instrumentation are enabled for both kepub and kepub3.
- Updated CLI/config/MHL/docs/tests to recognize and document kepub3.
Full Changelog: v1.7.1...v1.8.0