Split out header numbering into its own function.
Add the Index section. Need to handle sub-index things still.
Properly format propnames, and exclude them from the Index.
Remove duplicated property name formatting from transformPropdef.
Begin handling text replacement macros ([LONGSTATUS], etc.)
Add shortname as a metadata field.
Fill in more of the text macros.
Fill in the date-related text macros, and add [ISODATE].
Simplify by mashing .lines together into .html asap.