Dev edition todos

[domenic]

I spent some time today trying to re-create the dev edition from scratch using the Wattsi-produced output.

Here are the big to-dos I found:

• In headings and the TOC, section numbers need to be wrapped with <span class="secno">
• Splitting should be massively improved to give an outcome as good as the current dev edition. Probably every second-level section (e.g. 4.13) would get its own file.

Here are the minor todos that are fixable in postprocessing but maybe Wattsi should fix:

• Don't output both the brief TOC and the full TOC. Just the full TOC suffices (with a single "Table of Contents" heading).
• Remove the onload attribute from body.
• Body should get an "index" class for the TOC page (index.html)

[domenic]

Dupe of #27.