Confine vc-stay-local to CVS, because it was unusable in SVN.
Finish vc-stay-local containment.

* vc/vc.el, vc-hooks.el, and all backends: API simplification;
vc-stay-local-p and repository-hostname are no longer public
methods. Only the CVS and SVN backends used these, and the SVN
support was conditioned out because svn status -v is too slow.
The CVS back end retaiin this machibery and the vc-stay-local
configuration variable now only affects it.
Update some documentation changes and todo items.
Small but crucial change for new VC registration API.
Minor eww point placement fixup

* net/eww.el (eww): Leave point in a place that doesn't cause
scrolling when displaying "Loading...".
* .gitignore: Ignore loaddefs directly under lisp, and in sub-sub-directories