Update legal styles for Civil Law cases rendering

New code: no ```title``` = civil law case with title in ```short-title```.
It contains backward compatibility code for items already recorded with a "ghost" ```author``` (former hook to know if it's a civil law case in Zotero, and still used in other softwares.)
we did discuss this in the past, right? I'm still not very happy about using the note field here (and elsewhere), since this breaks the style for pretty much everything but Zotero.