Bug#682347: mark 'editor' virtual package name as obsolete

[Christoph Berg <myon@debian.org>]

Re: To Russ Allbery 2017-08-24 <[🔎] 20170824171653.r24gyar5mikyje7q@msg.df7cb.de>
> $ grep-dctrl -F Provides editor -nsPackage /var/lib/apt/lists/deb_debian_dists_sid_main_binary-amd64_Packages | xargs
> deutex edbrowse emacs25 emacs25-lucid emacs25-nox fte-console
> fte-terminal fte-xwindow jed xjed jove jupp le ledit levee lpe mg
> xul-ext-password-editor nano nano-tiny ne pluma rlfe rlwrap scite
> vigor vile xvile vim vim-athena vim-gtk vim-gtk3 vim-nox vim-tiny vis
> xul-ext-exteditor

There are some false positives in that list (deutex, ledit, pluma,
rlwrap, xul-ext-exteditor; "Provides: readline-editor" and similar),
but the list is still pretty long, I'd conclude.

Christoph