Various changes:

- Regneerate using latest Frog, using updated dependency Markdown,
  whose `display-xexpr` fixed a bug rendering &#nn; entities. The
  specific manifestation here was in Pygmentized code blocks: Single
  quote chars were being rendered as "39" instead of as "'".

- Set feed image bugs off. Doesn't really work unless the img is
  served from a server that can track this.