instead of `hx id=` (because the id= may pick up css unexpectedly.)
* in `linkyformat()`, don't pass in `&imaget` for image formats; pass
  in null instead and add a paranoia check to default to &imaget if
  the passed-in footnote is null.
* tweak the librarian generator so it doesn't require ln -s for static libs
* Repair a defect in the way >%class%es are handled;
  css class names are `{-_.A-Za-z}{-_.A-Za-z0-9}*` (plus some unicode characters
  which I don't support yet.)