Completed support for remarks, HTML and LaTeX
Fix table of contents default level
Front matter, title page, preface
Rename webpage boolean variable
Refactor document nodes to web pages
Both URL variants to sample article
Sage cells as display only, or as copies
Doctest creation: Sage display-only cells, minor improvements
Structural changes for front matter, common and HTML
Front matter presentation, HTML only
More flexible table-of-contents entries, HTML only