Search/replace "set" with "collection"

But not everywhere yet! This commit should be a no-op, for the
most part. It changes variable and function names, documentation,
etc, but the script still writes albums to a directory named "Sets."
Use new-style object syntax.
Bump copyright.
Fix bugs from aa7aa57 and add log statement.

The bugs were that I accidentally changed two Flickr API calls to use the
term "album" instead of "set," but the API still uses the old term.
One more no-op s/set/album/ change.
Rename directories from "Set" to "Album"