Make sure all arguments pub() passes to postMessage are structured-cloneable.

This avoids throwing an exception for code like 'catch(e) { pub("error", e); }'.
Addressed role of heading on h* elements

As per issue #370, the generation of role="heading"
on h* elements is not actually permitted by the HTML5
Recommendation and causes problems with some assistive
technology implementations.  Changed the strategy so
roles of heading are only placed on headings within notes and
issues.  In order to preserve the semantic data that explicit
roles can generate via RDFa, also added RDFa markup that maps
to the implied RDFa that would have been derived from the role
values were they still present.
Usse bibo:hasPart rather than bibo:Chapter as chapter reference. The bibo:Chapter property takes a literal as a value, and is intended for a chapter number rather than reference.
Use bibo:hasPart rather than bibo:Chapter as chapter reference. The bibo:Chapter property takes a literal as a value, and is intended for a chapter number rather than reference.
Remove support for RDFa 1.0, which was broken anyway.
Update references to put dc:requires/references on anchor, not dd. Add spec to check for this.
Move rdfa.js until after chapter ids are assigned. Create spec for bibo:Chapter.
Make sure abstract uses both bibo:hasPart and dc:abstract properties.
Don't create bibo:Chapter for abstract, toc, or sotd.
Don't remove @prefix when saving HTML. It is only generated if doRDFa is set.
Merge pull request #376 from darobin/develop

fix handling of empty string enums
Merge branch 'develop', remote branch 'origin' into develop
v3.2.31
Put editors in a list using rdf:first/rest/nil.
Change doRDFa to be a boolean, with boolean checks.
Fix broken contact markup.
Merge pull request #368 from jyasskin/feature/pub-non-cloneable

Make sure all arguments pub() passes to postMessage are structured-cloneable.
Merge pull request #371 from w3c/p-370

Addressed role of heading on h* elements
Merge branch 'feature/rdfa-lite' of git://github.com/gkellogg/respec into gkellogg-feature/rdfa-lite
Merge branch 'gkellogg-feature/rdfa-lite' into develop

Conflicts:
	js/core/rdfa.js

Needed to resolve conflicts with the changes from #371.
There was also a logic flaw that caused the RDFa annotations to be
applied to child elements of a section element even if they were not
headings.  Finally, a change from #371 was generating funny looking
IDs for headers on notes and issues.