Issue 3604: Fix function signature of overrideTimeSignatureSettings

Using fraction? rather than pair? is more discriminative, and using
the cheap-list? predicate rather than plain list? is not really a
significant time saver in a complex construct like this.
Doc: Color the Attic link (issue 3596).

This seems to be necessary each time a section is added.
Doc: Update authors (issue 3597).