anchor.diff:  * rethink how we're handling line heights for fonts, then document carefully
    ** look closer at line_height and line_height_length and see if we need to document other details
    ** allow line height to be set in more places (such as the prose for admonition, example, sidebar, etc)
  -* implement first-line indent for paragraphs (seems like conflict w/ our text formatter)
  +* (#191) implement first-line indent for paragraphs (seems like conflict w/ our text formatter)
    ** option to not indent first paragraph in section
    ** add indent/noindent options
    ** if you indent, perhaps drop the margin between paragraphs?
  
positive.code: * could use mask function to back up fields temporarily (used in prawn table)
  
  //-
  * not honoring align in abstract
  * don't style paragraph after abstract paragraph as lead (right?)
  * be able to control padding per column in footer
  
negative.code: 
  == TODO
  
  .1.5.0.alpha.17
  * (#85, PR sent) footnotes as chapter endnotes
  * (#891, PR available) FontAwesome 5 upgrade
   ** in what case do we need to lazy load the icon font in the font method?
  * (#606, PR available) running content on toc and title pages
  * does upgrading prawn-svg fix some issues? need to retest
  * (maybe) (#191, PR available) text indent for first line of paragraph
  * (maybe) add preamble to toc
  * (maybe) test suite
  * hexadecimal character refs
   ** should we go ahead and add nbsp too?
  
  .1.5.0.alpha.18
  * footnote logic: if putting the footnote on the page causes the content with the footnote reference to bump to the next page, the footnote simply follows the text to that page
  * setup asciidoctor-mathoid project, then mention it in the STEM support section
  * allow prose alignment to be set
  * should text alignment on list inherit to nested lists?
  * pass current styles downwards when parsing formatted text (see https://github.com/asciidoctor/asciidoctor-pdf/issues/854)
  * start the README with a proper introduction to Asciidoctor PDF (and not so focused on Prawn)
  * support unnumbered and no-bullet style on ordered list
   ** see https://github.com/asciidoctor/asciidoctor/pull/2286
  