previewCitationClusterStatic() + trial code against #6125

[fbennett]

We've crossed in the post. I've pushed a change to citeproc-js with a previewCitationClusterStatic() command, that accepts a single citation object as argument, and evaluates it based on the processor internal state, for the sake of simplicity.

There's a slight risk with this that a cite will not be correct, if the user has deleted citations or rearranged text with cut and paste, but it is very lightweight on client side, and handy, at least, as a way of testing whether the citeproc-js preview kit is working correctly.

I'm attaching a sample patch against #6125 that uses the new (1.0.28) API, and splices in this new preview command. It's not quite right yet -- the "insert" toggle needs some smartening up -- but it should at least show whether the citeproc-js preview stuff is stable.

[fbennett]

API extension proposal withdrawn, as discussion revealed that it's not particularly safe (and not particularly necessary) to make assumptions about document state in the processor.