Dear maintainers,

The vc-dir.el library hardcodes all of its faces to generic font-lock
ones.  This makes it impossible for users/themes to exert any control
over the presentation of those buffers.

In the attached patch, I do the following:

1. Define new faces.  Each has semantic value in that it applies to
   constructs implied by its name.

2. Cover the vc-git backend's implementation of extra vc-dir headers.
   This necessarily means that not all backends are brought to the same
   state after applying this patch.

3. Address a "FIXME" comment in vc-git.el concerning the use of a
   bespoke face for the stash header's value when that is empty.

4. Use new color combinations which conform with the WCAG AAA standard
   for color contrast against pure white/black (this standard pertains
   to legibility and is the highest of its kind).

With regard to point 2, I only use Git and thus cannot test the other
backends with the requisite degree of confidence.  Do you think I should
try regardless?  Or should we just support the Git backend and hope that
someone else will work on [some of] the other backends?

On point 4, please consider this a proposal: it is a highly opinionated
change.  If you feel we should in no way alienate existing users, I am
prepared to remove all colors and just :inherit from the faces that
applied before.

I attach a couple of screenshots showcasing the expected results.

Please let me know what you think.  I remain at your disposal for any
possible amendments to this patch, assuming you are willing to merge it.

All the best,
Protesilaos

-- 
Protesilaos Stavrou
protesilaos.com