anchor.diff:  * might be better to organize fragments of source chunks by lines (and pass that around) to simplify post-processing
   * support negative start value for list (#498)
     - need to count negative numbers in correct direction
  +* margins/paddings at page boundaries are strange, fragile
  +* implement margin collapsing (between blocks)
  +  - would eliminate need for negative padding for blockquote
   * SIMPLE: submit pastie theme for Rouge upstream
  +* bw theme for CodeRay (or Rouge) to match output of Pygments bw
   * the nested? method on list isn't checking if nested inside a block inside a list
   * wrapped lines in source listing should be indented to account for line number gutter (#504)
   * add sample SVG to content of chronicles-example.adoc (we do already use one for title page)
  
positive.code: * rename "theme" to "style"?
  * restrict custom theme path to jail (or load from load_path)
  * implement convert_toc
  * only create title page if doctype=book
  * italic text in a line of text styled as bold in the theme loses its bold style
  
  * introduce method for start_initial_page?
  * make outline a document option (perhaps "outline" like "toc")
  * shrink / squeeze source code to avoid wrapping (see original impl in nfjsmag, also shrink_to_fit)
  * add bench/ directory for the script to test the speed of the formatted text parser
  * start page numbering on page 1 (use /PageLabels reference to make i the title page number)
    - add this feature upstream to Prawn
  * *report image only page w/ stamps corruption issue to Prawn*
  * add /PageMode /UseOutlines
  * what does fopub do to calculate scaling images? reduces width more?
  * replace tabs with spaces in source code (Asciidoctor core change?)
  * preamble on separate page?
  * part on separate page for book doctype? (which other sections?)
  * make default image scale width a theme setting
  * cli arguments
    - theme (pdf-style, pdf-stylesdir)
    - enable/disable writing pdfmarks file
    - optimize-pdf
  * section numbering
  * implement footnotes correctly
  * table footer
  * flesh out outline more
  * flesh out title page more
    - document subtitle (partially solved)
  * don't create title page for article doctype
  * implement toc and activate if toc is set on document (need to reorder pages)
  * inline image
  * callbacks for title page, new part, new chapter, etc
  * split out render methods for chapter, part, section, etc
  * custom subs in verbatim blocks
  * captions/titles on all blocks that support them
  * make font size and character spacing scaling of inline code part of theme
  * customizable character spacing
  * might be able to avoid dry run for listing/literal in obvious cases
  * implement index of index terms
  * bw theme for CodeRay to match output of Pygments bw
  * inline tabs should be replaced in layout_prose (etc) when normalize is enabled
  
  * use treetop to parse and evaluate theme file
  * make source code highlighting theme configurable (should be now, but has problems with conums); still?
  * use or don't use pad method? check performance
  
  == Major Milestones
  
  * add a test suite
  * refactor as Prawn View
  
negative.code: * document all permutations of image sizing
  * set vposition on title page logo image explicitly to avoid page overrun?
  
  * allow pdf-page-margin to be set in document
    - this is slighly more complicated now that we have mirror margins; perhaps can't set those from document?
  * verse has problems with wrapping if line is long (in what way?)
  * allow default kerning to be set using theme
  * keep line comment in front of callout number to aid copying?
  * rework pull request for source line numbers (combine with restore conum logic if conums are enabled)
    - also combine with the preserve_space logic
  * allow front cover and back cover image to be defined in theme as fallback; document in theming-guide
  * should we shorten the keys to front-cover and back-cover (since image is implied?)
  * keep caption with table (check for sufficient space); only for top placement since bottom placement is much harder
  * allow valign to be set on image block (vertical center in page for things like slides)
  