anchor.diff:  * move check for node.title? inside layout_caption
   * theme idea / tester: see sandbox/ebook-learn_version_control_with_git-SAMPLE.pdf
   * make alternating page title position optional (via theme?)
  -* page numbers are off in Clojure Cookbook
  +* BUG: page numbers are off in Clojure Cookbook
  +* image in header / banner (need to implement a masthead)
   
   * enable pagenums attribute by default (may require changes to how we handle attributes)
   * start page numbering on first page if no title page
  
positive.code: 
  == TODO
  
  * nested keep_together logic is broken (e.g., example inside example, listing inside sidebar, etc)
  * refactor as Prawn view to avoid method name conflicts
  * SVG image is getting cut off when at boundary of page
  * create proper default (Asciidoctor) theme
  * start number for conum in theme
  
negative.code: * flesh out title page more
    - document subtitle (partially solved)
  * don't create title page for article doctype
  * chapter name in footer (need a proper hook for writing to the footer; perhaps also template in theme for footer text)
  * 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
  