Locales conversion table, and CSL schema for MLZ

Two small updates:

  1. I added a conversion table for locale codes and language names (limited
    to the locale codes for which we have CSL locale files):

I added this since I stumbled on

http://crosscite.org/citeproc/, and I think users shouldn’t have to deal
with locale codes if possible.

  1. I also completed an extension schema for Multilingual Zotero:

Frank forked the CSL schema for his work on multilingual and law styles (
http://citationstylist.org/). To make maintenance easier I turned this into
an extension schema that uses the official schema as its basis, redefining
only those parts that needed changing. Ultimately Frank and I would like to
merge as much as possible of this into the official schema, but that might
take a while. I want to stress that while Frank and I work on this, the
extension schema is a fork independent of the CSL project. We in no way
promise any kind of cross compatibility with official CSL styles, and the
extension schema may be changed at a whim’s notice.