bug#15687: 24.3.50; custom themes: disabling does not restore initial configuration

[Drew Adams <drew.adams@oracle.com>]

Please read the bug report.  It includes the case where all themes
that have ever been applied have since been disabled.  That does not
restore all other customizations that were in effect before theming.
That's all.

If you need a recipe, emacs -Q, load oneonone.el, then doremi.el and
doremi-cmd.el.  Then cycle among themes, using `doremi-custom-themes+'.
Use `C-g' to cancel.  The initial state is not restored.  Nothing
close to it.  Not for any existing frames.

Sure, if you then create a new frame, things will look generally OK
in that frame.  But the state of any existing frames has been altered
and not restored.  Disabling a theme does not undo its effect wrt
Emacs in general.  It simply disables one theme wrt other themes
(including wrt all other themes).

In addition, I see no way to take a snapshot of the current Emacs
state as a theme, or even as a pseudo theme, to which one can revert.

This is something that is trivial with color themes - just call
`color-theme-make-snapshot'.

Try the same thing, but with command `doremi-color-themes+'.
No problem.