References updates

[katamartin]

This PR makes a few updates to the way references are tracked in order to support some additional features:

• Automatically number references based on the order in which the inline Cite/Sidenotes are rendered
  • Previously, references.js numbered the references based on the order in which they were threaded through to ReferencesProvider. This (1) relied on object ordering and (2) required consumers to manually sort the references object.
• Add a PrintedFootnotes section to the bottom of Article which displays a list of references using the Endnote layout (isolated to printing using '@media print')
  • Previously, citation contents were hidden on print because of the mobile styles that are applied.
  • Addresses references point in Improved printing to PDF research#206.
  • See example PDF (also generated using scrambled references and two inline Sidenotes).
• Support additional, notes added inline via the Sidenote component
  • Allows non-citation notes to be easily added in text. For example, adding:

    ...or macronutrient fertilizers.<Sidenote>Sample custom note defined inline.</Sidenote>
    

    to this line in the seaweed farming article would render:
    

closes carbonplan/research#205

[freeman-lab]

This looks really clean to me! And super excited for this functionality. Only one question: what happens when a reference is repeated twice? I'm not sure we'll have this often (or ever), but I seem to recall we've avoided it because we were worried it would screw things up.

From a rendering standpoint, I think what we want is if <Cite id='example'/> appears, say, second, it has the superscript number 2 and we have the full citation to the right, and then if <Cite id='example'/> appears again later on in the article, the superscript number 2 appears but we don't repeat the full citation again (because we have it above), and the numbering continues as though there was no repeat. Is that easy to support given this implementation?

[katamartin]

Ah good question! I added in a hide prop, which will allow a repeated citation to be omitted from the inline references. This will have to be added manually for repeated references, which I think is desirable because we currently don't handle scrolling to references.

Also while I was touching the logic that handles groups of IDs, I tweaked the mobile rendering so that all references can be opened inline:

Previously, this was rendered using 3-6 which we can still use for desktop + printing (see updated example):

[freeman-lab]

lgtm! and very nice tweak for mobile, that's smart