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.)
Oh... I wasn't aware of that (weird) Mendeley mapping!
Let me check with some other users.