bug#14964: 24.3.50; doc of `compare-window-configurations'

[Drew Adams]

> https://github.com/tlh/workgroups.el

Yes, it is good to point to that, as another example of readable window
configurations.

You mentioned frame configurations too, but working groups are not,
according to what I read in the doc and see in the code, frame
configurations.  Rather, a workgroup is a set of window configurations
for a single frame.  From the doc:

  Q: What's the difference between a "window configuration", a "wconfig"
     and a "workgroup"?
  A: A "window configuration" is Emacs' opaque internal representation of
     most of the state of one frame. A "wconfig" is Workgroups' independent,
     translucent window configuration object. And a "workgroup" is a named
     set of multiple wconfigs (one base config, and then a working config
     for each frame).

So yes, this could inform what we do wrt Emacs window configurations.

It is also an example of the kinds of things that a library or a user
might want to do with persistent window configurations.  And it is another
argument for having a standard, transparent, readable window-configuration
structure (whatever form the implementation might take).