Add vimpulse-want-quit-like-Vim customization variable.

[Štěpán Němec]

Vegard,

I don't understand purpose or motivation of this change (commit
af7bc2369c72a9), could you please comment (and could you (and others
whom it may concern) *please* add such comments to the commit messages
as well)?

Apart from the fact that I don't get why you made the change in the
first place, I see other issues as well: Viper already includes a :quit
command, which is about as faithful to the Vim behaviour as the
trivial version used by Vimpulse.[1] Now you add a variable whose name
suggests that it will be "like Vim", but it actually triggers the
Vimpulse behaviour...

[I don't care other than that it's weird (I don't use any Ex commands
at all).]

Thanks,

Štěpán

[1] Actually, each of the commands, i.e. `ex-quit' on one hand and the
Vimpulse version on the other, pick a different part of what Vim's :quit
command does.