[sudo-users] per-user editor for visudo

[balducci at units.it]

> > committed a change in visudo to check the SUDO_USER environment
> > variable and use that if it is set and visudo is run as root.
> > A better option might be for sudo to pass the editor for visudo on
> > the command line, which I am considering.
> 
> I'll build the latest commit and report

just built and installed latest rev (10571) and it seems to work
flawlessly: I can change the editor for user balducci like this:

Defaults:balducci   editor=/usr/bin/<whatever>, ....

without the need for anything else (EDITOR/VISUAL export or "Defaults
editor=..." or whatever)

great.

and thank you very much again for your valuable work and for making it
freely available

ciao
-gabriele