Adding "self" links to dependents

Quick FYI:

Dan Stillman just added support for auto-updating CSL styles for
Zotero’s next big update* (hurrah). Since we’d also want dependent
styles to auto-update, it makes sense to give them “self” links (most
dependents currently don’t have these). As with independent styles,
there is some redundancy involved, since we currently use the same URL
for the style ID and “self” link. Unless I hear any objections I’ll
add the links in the next day or two.