Sort references by short name

The previous code relied on the (undefined) iteration order of sets.
(I happened to get a different order on css-syntax.)

The sorting criteria is kind of arbitrary.
It could be by order of first reference,
or anything we know about the refs.
Merge pull request #4 from SimonSapin/sort-refs

Sort references by short name
Merge pull request #2 from SimonSapin/master

Add a setup.py
Make undefined properties/terms fatal errors, now that you can instruct the processor to ignore them.
Attempt to fix html5lib-1.0b error with unicode encoding.
Serialize the final document using the html5lib serializer, so SVG serializes properly.
Use UTC for the default date

It seems to make a little more sense, though I’m not sure.
Add test suite metadata.
Merge pull request #5 from SimonSapin/patch-1

Use UTC for the default date
Add alphabetical attributes to the serializer, so we get less diff churn of the generated spec due to attribute order being unpredictable.
Make both contact-page and contact-email editor formats similar.
Fix multi-author biblio stringification.
Tag all <dfn>s with what type of term they're deffining. Handle value definitions separately from terms.
Add a few linebreaks in the auto-genned elements, so diff will be more accurate and have less churn.
Rejigger how I add things to headings/ToCs. Add a section link to headings.
Fix some typos.
Catch incorrectly-formatted metadata lines. Add beginning code for parsing xref data.
Move biblio stuff and u() function to separate modules.
Better error-handling for badly-formatted dates.
More toc fixup to produce valid HTML.