anchor.diff:  * only use the inverted sizes for chapter title if publication-type is not book
   * use overflow-wrap consistently
   * use same logic for chapter title in document header as in TOC (level-1 section title should not be detected)
  -* when chapter for xref is unknown, don't emit a link (we can't be so sure for refids atm)
  -* make sure every doc is assigned an ID (perhaps it already is) so we don't need to rely on the docname attr as a fallback
  - ** I believe this is already true; just remove hack
  -* allow imagesdir to be outside of docdir (#22)
   * don't add image from front matter if already referenced by chapter
   * add document filename to warn messages (added for some)
  -* look for front-matter.html relative to docdir (or base_dir?); also allow front-matter.xhtml
  +* allow front-matter.xhtml
   * reorder sections in README; needs to flow a bit better...Getting Started is too large & after Structuring your Manuscript
  -* add helper to resolve imagesdir
   * support inline SVG
   * describe the leveloffset setting in more detail in the README
   * link to https://medium.com/@sandersk/responsive-ebook-design-a-primer-8bba01328219 in style section in README
  -* why don't we just use the chapter filename as the id?
   * only uppercase document title if detected in CSS
   * add empty front matter page in kf8 version if one is specified to allow navigation to first entry from TOC
    ** why can't we navigate to first chapter on Kindle from TOC?
   * document more clearly how to provide your own CSS
    ** currently it's not possible to override the epub3-fonts.css (though it should be)
  -* add nav entry for cover if format != :kf8 ?
   * cleanup this sanitize XML stuff; move to Asciidoctor::Helpers?
    ** also need an upcase_pcdata
   * allow role to be applied to chapter (which means the role must be on the document)
  
positive.code: //^
  == REVIEW
  
  * conversion of single file (no master document)
  * package images referenced by content
  * how custom CSS is specified
  
  == NOTES
  
negative.code: * MEDIUM: source highlighting using Rouge (instead of Pygments)
  * MEDIUM: to remove text indent in mobi7, set width="0pt" (text-indent) on <p> tag; also set height="1em" (margin top)
  * MEDIUM: create back link in bibliography entry for each reference to it (currently only the first)
  * implement checklists
  
  //^
  .Packager
  * HIGH: add NOTICE.adoc to e-book archive
  * HIGH: minimize CSS (and any other assets worth minimizing)
  * HIGH: add back cover if specified
  * MEDIUM: add JavaScript to nav.xhtml to add class for epubReadingSystem to body
  * MEDIUM: rename OEBPS folder to EPUB
  * MEDIUM: option to add nav.xhtml to navigation flow?
  * MEDIUM: add Pygments stylesheet to EPUB archive if pygments-css=class
  * support subtitle as separate from main title in package metadata
  * support collection title in package metadata
  
  .Fonts
  * recreate ellipses in M+ 1p to be on baseline
  
  .Stylesheet
  