Have more targets for rendered output

[swfsql]

• book:

  • A4paper for print [WIP]
  • letterpaper for print
  • ebook
  • ebook mobile
  • epub
  • html

• article:

  • A4paper for print
  • letterpaper for print
  • ebook
  • ebook mobile
  • epub

• The book format has parts (book parts) possibility, article has not.

• The book format has full page covers for all formats, where article only has full page covers for ebook mobile and epub.

• For printing documents should be double-faced (asymmetric margins), where ebook type, for being electronic only, is considered single-facing.

• Electronic formats doesn't need to have a table of contents, since this information can be shown by almost all pdf/epub file readers.

• Ebook targets tablets and PCs, with small margins but still around 66 characters per line; Ebook mobile should have even smaller margins, and around 45~50 characters per line; Epub doesn't have that (it's adjusted automatically).

• A4 paper is the most commonly used papersize, so should be more accessible; letterpaper is the most common on various countries. Supporting both would mean virtually supporting all of the cheap paper available for anyone.

Moved from ancap-ch/from-en#1630