Color themes

[Chong Yidong]

Many of you are probably aware of a package called color-theme.el,
currently maintained by Xavier Maillard.  This package provides a
relatively easy way to choose from a list of pre-selected "color
themes" for font-lock keywords.  I think this kind of functionality
would be good.  For new users who dislike the default color palette,
there's currently no easy way to choose a different palette.

Ideally, there should be a submenu in the menu-bar, under Options, to
select a color theme (or whatever we end up calling it).

However, I'm ambivalent about how color-theme.el is written.  From a
perfunctory inspection of the code, it looks like it sets up some
infrastructure for defining color-themes that I'm not sure is a good
fit for Emacs.  In particular, it might be cleaner to define color
themes using Custom Themes, which were implemented in Emacs 22 and
meshes with the Customize facility.  I might be wrong, however, so
comments are welcome.

At this early stage, I haven't looked into the copyright assignment
issue for color-theme.el.  Assuming papers aren't a problem, I'm
thinking we could absorb part of the color-theme project, i.e. the
color settings that they've collected, and rewrite the theme-choosing
infrastructure based on Custom Themes.

Any thoughts?