The rich text editor needs a Small Caps option

[SteveRidout]

This will be trickier to implement than the existing formatting options since there is no simple 'smallcaps' command to pass to document.execCommand() (see https://developer.mozilla.org/en-US/docs/Rich-Text_Editing_in_Mozilla#Executing_Commands)

The relevant output it needs to match in the citeproc-js output is:

<span style="font-variant:small-caps;">This text in small caps</span>

Perhaps this should be converted to something smaller for the search algorithm, e.g. <sc></sc> so it doesn't disproportionately affect the edit distances. Or, better yet, experiment with other ways to fairly calculate edit distances of tagged content.