bug#6693: 24.0.50; font-lock-(builtin|doc) faces are *way* too close

[Drew Adams]

> As for font-lock-builtin-face, changing it back to Orchid is no good;
> that shade is far too light, at least on the LCD monitors I've used
> Emacs on.

FWIW, I disagree (on the LCD monitors I've used).

> I wouldn't mind changing it to something completely different
> though, e.g. midnight blue.  We have too may purplish colors in the
> default palette anyway.

A priori I have nothing against changing it to something completely different.
Dunno about midnight blue.

I mainly see font-lock with Emacs-Lisp code (in my use), and ther is nothing
similar to midnight blue there.  On the other hand, midnight blue is not too
different from black (the default foreground).  `list-faces-display' shows
nothing super close to midnight blue (and nothing close at all in the font-lock
faces).  But it looks like the medium blue of `minibuffer-prompt-face' is
already quite dark and not too easily distinguished from black.  My guess is
that midnight blue would be too dark (too close to black).

I suggest that you do your best to pick another color, if you disagree with
`Orchid', and that people try it for a while to see (discuss).

This is obviously not the most important bug.  But if we can better separate
these two faces that would be good.

Note that (at least in Emacs-Lisp code) this face is used for coloring only
keywords: `:type', `:group' etc.  It is not for coloring large spans of text
that someone needs to read.  The point in coloring the keywords is just to draw
attention - they do not need to be super-readable (as does a doc string, for
instance).  That's another reason I don't think a face like `Orchid' was a bad
choice.