Rename vc-name to vc-master-rename.

* vc-hooks.el, vc-rcs.el, vc-sccs.el: vc-name -> vc-master-name.  This
is preaparatory to isolating all the 'master' functions used only by
the file-oriented back ends.  With this done first, the substantive
diffs will be easier to read.
Isolating support code for the file-granularity back ends: the easy part.

* vc-filewise.el: New file to isolate code used only by the
file-oriented back ends (SCCS/RCS/CVS/SRC) which should not live in
vc.el and certainly not in vc-hooks.el.