[osis-core] Conclusion of "scope" attribute on <div>.

[Todd Tillinghast]

We discussed but I don't that we resolved anything related to
introducing an attribute called "scope" for <div> for use rather than
"osisRef" to indicate the range of osisIDs contained within the element.

I OK with adding a "scope" attribute that has the same regular
expression as osisRef.  

If we do add scope will we leave osisRef for the other uses already
discussed?

Todd