bug#10150: deactive->inactive, inactivate->deactivate spelling fixes

[Drew Adams]

> > inactivate vt to make inactive - inactivation n
> 
> Right.  So the only thing that actually needs a fix is
> follow-deactive-menu.

"Needs", perhaps, if the argument is only wrt English usage and not software use
and maintenance.  I agree that the word "inactivate" is not inappropriate.  (It
has the additional advantage of being similar to the term used for this in some
other languages.)

However, it also makes sense for Emacs to pick one term for this and stick to
it.  I suggest moving to "deactivate" everywhere, but of course by proper
aliasing and deprecation, and with no hurry to desupport the deprecated names
(no need).