Ditz issue update
Add macros for defining properties with WEC attrs

Also change call sites to use these macros.  For now, the macros just
call the existing def_prop_xxx() functions, but because there are
relatively many call sites, these can be footprint optimized later.
Merge branch 'defprop-wec-macro'
first cut at reducing the boilerplate in api doc entries: Prototype, Stack, and Summary are pretty self-evident; Example and See also are still left as headings
restore headings to markup for better text browser compatibility, but add classes for them so that css hacks can be used for layout tweaks
layout prototype for api sections with wide window
Fix API entry heading vertical alignment

Styling changes necessary to make the API entry headings (such as
'Prototype' etc) to align vertically when browser window is wide.
Getting the alignment to work requires awkward margin hacks.

Also reimplement CSS styling for stacks to be more simple.
Ditz issue update