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.)
Regular notes in Mendeley (and IIRC Papers) are mapped to ```note```--so while it doesn't break the style in the literal sense of the work, it does make it pretty much unusable for anyone using Notes in Mendeley (I'd prefer they mapped that to ```annote```, but I doubt that's going to happen any time soon. I've asked about that months ago. 
As CSL is used more widely, our preference is to have the style as little Zotero-specific as possible. I realize that this won't be entirely possible for legal styles given the limitations of both CSL and the various reference managers, so this isn't a strict rule by any means, so if you're telling me that this can't be done properly without, we'll keep it in.
But if this optional, I think general usability of the style will benefit from taking it out.