Toggle gnome-panel instead of restarting it

Since Ubuntu 14.04 the auto-hiding gnome-panel in XMonad doesn't really
work well anymore. So now just have a shortcut to start and kill it for
whenever it is needed.
Disable Android Manifest file discovery in vim
Simplify GIMP handling

Throw all GIMP windows onto the gimp workspace and then just use it in
single window mode.
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