Slow merge of vc.el begins: "focus version"

[Eric S. Raymond]

Dan Nicolaescu did an extremely helpful thing by reordering the code
in vc.el, but as I feared the diff is still quite large and noisy.
There was really no avoiding this, as large portions of the mode 
needed a rewrite.

In order to make auditing of the diff more feasible, I'm going to
merge into head some of the bits from my version that don't make logic
changes.  I will probably start by merging, into both code and manual,
the "workfile version" -> "focus version" change.  It is responsible
for a lot of the noise.

I am not really happy about introducing a new term, especially one
that isn't lifted from VCS terminology already current.  But, as I
explained to Dan, none of the VCSes have evolved an unambiguous term
of art for this.  

"Workfile version" is, I believe, strictly an Emacsism these days.  It
becomes inappropriate and misleading when we are speaking of a VCS in
which version numbers are not a per-file property but associated with
changesets.  This is true of all VCSes from Subversion onwards.

I suppose "working-copy version" might be more explicit while
avoiding the problem.  I might switch both my code and the Emacs
head revision to use that.  I'll have to try altering the manual
both ways and seeing how it reads.
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>

To make inexpensive guns impossible to get is to say that you're
putting a money test on getting a gun.  It's racism in its worst form.
        -- Roy Innis, president of the Congress of Racial Equality (CORE), 1988