anchor.diff:  * add a test suite
   * refactor as Prawn View
   * add support for footnotes (as article or chapter endnotes)
  -* add support for nested tables by writing custom Table::Cell implementation
   * pass styles downwards to child elements in formatted text transform instead of decorating on way out of hierarchy
   * rework text handling in Prawn to support line height natively
   * margin collapsing (like CSS)
  +* use proper model to handle the page number to current part/chapter/section mapping in running content
  +* cleanup/reorganize imports in lib/asciidoctor/converter.rb
   
   == Documentation
   
  
positive.code: * theme idea / tester: see sandbox/ebook-learn_version_control_with_git-SAMPLE.pdf
  * make alternating page title position optional (via theme?)
  * fix passthrough placeholders that get caught up in syntax highlighting (see https://github.com/asciidoctor/asciidoctor/blob/master/test/blocks_test.rb#L2258-L2277)
  * FILE ISSUE list Preamble in TOC
    - perhaps only if it has a title? or should we use a default title if one isn't specified?
  * honor font defs in SVG (to get M+ 1p); prawn-svg supports loading fonts; need to pass fonts to prawn-svg
  * should we support % as a unit in theme (divides by 100 and sets float value)?
  * disable monospace font color (and family?) in headings
  
negative.code: * numbering for appendix subsections is not correct; should be A.1, A.2 (#627)
    - seems like an issue in core too
  * BUG: http://asciidoctor.org[Asciidoctor] surrounded by smart quotes doesn't get translated to a link (as it should)
  * FILE ISSUE: draw border for quote/verse block on right if text is aligned to the right
  * Prawn should not move cursor before placing image if image exceeds height of bounding box
    - ^ workaround in place by overriding move_text_position
  * part title / number (#597)
  