4.9.0

Changelog

[4677633] Added a new syntax to force page breaks (compatible with LeanPub and Marked)
[d8e8f32] Added support for all kinds of admonitions (note, tip, sidebar, warnings, ...)
[eb96ba9] Greatly improved themes and default templates
[4c8323f] Fixed unit tests
[dbfbca8] Added option to include html toc in ebook
[77d7c74] Avoid creating an extra folder into zip file.
[913da20] Generate unique id for custom css in content.opf
[82deb31] Added inclusion of images that are not figures
[a652216] Improved documentation
[6689ea1] Include in navigational toc only 'tocable' items
[5ead921] Fix formattin of TOC items whithout label
[e22a608] Epub: do not use twig namespaces when rendering templates as this precludes the usage of customized templates per ebook
[cde1137] correct images label when there is a title
[094a818] Added a new 'chunk_level' option to 'html_chunked' format.
[02494ab] Added images_base_dir option to set the base directory for web images.
[6414218] Added support for books written in Japanese, Russian, Turkish, Greek, Czech, LAtvian, Polish and Ukrainian.