misc/vim: Separate package and package members.
This change allow to godoc:
    :Godoc github.com/mattn/go-gtk/gtk
    :Godoc github.com/mattn/go-gtk/gtk NewWindow
    :Godoc encoding/json
    :Godoc encoding/json Marshal

R=golang-dev, dsymonds
CC=golang-dev
https://codereview.appspot.com/14171043

Committer: David Symonds <dsymonds@golang.org>