add @font-face rules for the CJK radicals and extension B glyphs used.

[Pomax]

This would require:

• inventory which characters are used from which blocks (this should be easily scriptable: just run through the content files and build a list of used codepoints, then dump that to a file)
• determine which free font(s) can act as basis for creating a dedicated subset font
  • the book itself already uses HAN NOM A and B, so we might be able to just subset out of those.
  • alternatively Hanazono might work?
• making a subset WOFF file with radical coverage.